diff --git a/app.py b/app.py
index 832a0ba..e3197b0 100644
--- a/app.py
+++ b/app.py
@@ -357,7 +357,7 @@ def loadout():
     tab  = request.args.get("tab", "guns")
     sort = request.args.get("sort", "weight_asc")
 
-    guns = armor = helmets = headwear = backpacks = rigs = []
+    guns = armor = helmets = headwear = backpacks = rigs = plates = []
     builder_guns = builder_armor = builder_helmets = builder_rigs = builder_backpacks = []
     requires = request.args.getlist("requires")  # list of slot_nameids that must exist
     min_class    = request.args.get("min_class",    0, type=int)
@@ -443,6 +443,14 @@ def loadout():
             ORDER BY {sort_frag}
         """, (min_capacity, min_capacity, min_class, min_class)).fetchall()
 
+    elif tab == "plates":
+        plates = conn.execute(f"""
+            SELECT * FROM gear_items
+            WHERE category = 'plate'
+              AND (? = 0 OR armor_class >= ?)
+            ORDER BY {sort_frag}
+        """, (min_class, min_class)).fetchall()
+
     elif tab == "builder":
         builder_guns      = conn.execute("SELECT id, name, weight_kg FROM gear_items WHERE category='gun'      ORDER BY name").fetchall()
         builder_armor     = conn.execute("SELECT id, name, weight_kg FROM gear_items WHERE category='armor'    ORDER BY name").fetchall()
@@ -450,12 +458,16 @@ def loadout():
         builder_rigs      = conn.execute("SELECT id, name, weight_kg FROM gear_items WHERE category='rig'      ORDER BY name").fetchall()
         builder_backpacks = conn.execute("SELECT id, name, weight_kg FROM gear_items WHERE category='backpack' ORDER BY name").fetchall()
 
+    # IDs of carriers that have at least one open plate slot (shell weight only)
+    open_slot_rows = conn.execute("SELECT DISTINCT carrier_id FROM armor_open_slots").fetchall()
+    carrier_ids_with_open_slots = {row["carrier_id"] for row in open_slot_rows}
+
     conn.close()
     return render_template(
         "loadout.html",
         tab=tab, sort=sort,
         guns=guns, armor=armor, helmets=helmets, headwear=headwear,
-        backpacks=backpacks, rigs=rigs,
+        backpacks=backpacks, rigs=rigs, plates=plates,
         slot_filters=LOADOUT_SLOT_FILTERS,
         requires=requires,
         min_class=min_class, min_capacity=min_capacity,
@@ -464,6 +476,7 @@ def loadout():
         builder_helmets=builder_helmets,
         builder_rigs=builder_rigs,
         builder_backpacks=builder_backpacks,
+        carrier_ids_with_open_slots=carrier_ids_with_open_slots,
     )
 
 
@@ -506,17 +519,19 @@ def gun_detail(gun_id):
         if row["mod_id"]:
             slots[sid]["mods"].append(dict(row))
 
-    # Key slots to show at top (highlighted)
+    # Split into required vs optional slots
     KEY_SLOTS = {"mod_muzzle", "mod_magazine"}
     ordered_slots = [slots[s] for s in slot_order]
-    key_slots   = [s for s in ordered_slots if s["slot_nameid"] in KEY_SLOTS]
-    other_slots = [s for s in ordered_slots if s["slot_nameid"] not in KEY_SLOTS]
+    # Required slots (always needed) shown at top — key slots (magazine/muzzle) highlighted
+    key_slots      = [s for s in ordered_slots if s["required"] and s["slot_nameid"] in KEY_SLOTS]
+    req_slots      = [s for s in ordered_slots if s["required"] and s["slot_nameid"] not in KEY_SLOTS]
+    optional_slots = [s for s in ordered_slots if not s["required"]]
 
-    # Lightest total (base + lightest per slot)
+    # Lightest total (base + lightest per REQUIRED slot only)
     lightest_total = (gun["weight_kg"] or 0) + sum(
         s["mods"][0]["weight_kg"]
         for s in ordered_slots
-        if s["mods"] and s["mods"][0]["weight_kg"] is not None
+        if s["required"] and s["mods"] and s["mods"][0]["weight_kg"] is not None
     )
 
     conn.close()
@@ -524,7 +539,8 @@ def gun_detail(gun_id):
         "gun_detail.html",
         gun=gun,
         key_slots=key_slots,
-        other_slots=other_slots,
+        req_slots=req_slots,
+        optional_slots=optional_slots,
         lightest_total=lightest_total,
     )
 
@@ -571,6 +587,45 @@ def gun_slots_json(gun_id):
     return jsonify(result)
 
 
+@app.route("/loadout/carrier/<carrier_id>/slots.json")
+def carrier_slots_json(carrier_id):
+    """Returns open plate slots and allowed plates for a carrier (armor or rig)."""
+    conn = get_db()
+    rows = conn.execute("""
+        SELECT aos.slot_nameid, aos.zones,
+               p.id AS plate_id, p.name AS plate_name, p.short_name AS plate_short,
+               p.weight_kg, p.armor_class, p.durability, p.material
+        FROM armor_open_slots aos
+        LEFT JOIN armor_slot_plates asp ON asp.carrier_id = aos.carrier_id
+            AND asp.slot_nameid = aos.slot_nameid
+        LEFT JOIN gear_items p ON p.id = asp.plate_id
+        WHERE aos.carrier_id = ?
+        ORDER BY aos.slot_nameid, p.armor_class DESC, p.weight_kg ASC
+    """, (carrier_id,)).fetchall()
+    conn.close()
+
+    # Group by slot
+    slots = {}
+    slot_order = []
+    for row in rows:
+        sn = row["slot_nameid"]
+        if sn not in slots:
+            slots[sn] = {"slot_nameid": sn, "zones": row["zones"], "plates": []}
+            slot_order.append(sn)
+        if row["plate_id"]:
+            slots[sn]["plates"].append({
+                "id":         row["plate_id"],
+                "name":       row["plate_name"],
+                "short_name": row["plate_short"],
+                "weight_kg":  row["weight_kg"],
+                "armor_class": row["armor_class"],
+                "durability": row["durability"],
+                "material":   row["material"],
+            })
+
+    return jsonify([slots[s] for s in slot_order])
+
+
 @app.route("/loadout/save-build", methods=["POST"])
 def save_build():
     data = request.get_json() or {}
diff --git a/import_gear.py b/import_gear.py
index 405658a..bafa52e 100644
--- a/import_gear.py
+++ b/import_gear.py
@@ -64,6 +64,14 @@ GRAPHQL_QUERY_GEAR = """
         durability
         material { name }
         zones
+        armorSlots {
+          __typename
+          ... on ItemArmorSlotOpen {
+            nameId
+            zones
+            allowedPlates { id }
+          }
+        }
       }
     }
   }
@@ -112,6 +120,26 @@ GRAPHQL_QUERY_GEAR = """
         class
         durability
         zones
+        armorSlots {
+          __typename
+          ... on ItemArmorSlotOpen {
+            nameId
+            zones
+            allowedPlates { id }
+          }
+        }
+      }
+    }
+  }
+
+  plates: items(types: [armorPlate]) {
+    id name shortName weight gridImageLink wikiLink
+    properties {
+      ... on ItemPropertiesArmorAttachment {
+        class
+        durability
+        material { name }
+        zones
       }
     }
   }
@@ -211,6 +239,7 @@ def import_weapons(conn, weapons):
 def import_armor(conn, items):
     cursor = conn.cursor()
     counts = {"inserted": 0, "updated": 0, "skipped": 0}
+    slot_data = {}  # carrier_id -> armorSlots list
     for item in items:
         item_id = item.get("id")
         name = item.get("name")
@@ -229,8 +258,11 @@ def import_armor(conn, items):
             zones=zones,
         )
         counts[result] += 1
+        armor_slots = props.get("armorSlots") or []
+        if armor_slots:
+            slot_data[item_id] = armor_slots
     conn.commit()
-    return counts
+    return counts, slot_data
 
 
 def import_helmets(conn, items):
@@ -291,6 +323,7 @@ def import_backpacks(conn, items):
 def import_rigs(conn, items):
     cursor = conn.cursor()
     counts = {"inserted": 0, "updated": 0, "skipped": 0}
+    slot_data = {}  # carrier_id -> armorSlots list
     for item in items:
         item_id = item.get("id")
         name = item.get("name")
@@ -308,10 +341,75 @@ def import_rigs(conn, items):
             zones=zones,
         )
         counts[result] += 1
+        armor_slots = props.get("armorSlots") or []
+        if armor_slots:
+            slot_data[item_id] = armor_slots
+    conn.commit()
+    return counts, slot_data
+
+
+def import_plates(conn, items):
+    cursor = conn.cursor()
+    counts = {"inserted": 0, "updated": 0, "skipped": 0}
+    for item in items:
+        item_id = item.get("id")
+        name = item.get("name")
+        if not item_id or not name:
+            counts["skipped"] += 1
+            continue
+        props = item.get("properties") or {}
+        material = (props.get("material") or {}).get("name")
+        zones = ",".join(props.get("zones") or []) or None
+        result = upsert_item(
+            cursor, item_id, name, item.get("shortName"), "plate", item.get("weight"),
+            item.get("gridImageLink"), item.get("wikiLink"),
+            armor_class=props.get("class"),
+            durability=props.get("durability"),
+            material=material,
+            zones=zones,
+        )
+        counts[result] += 1
     conn.commit()
     return counts
 
 
+def import_armor_open_slots(conn, carrier_id, armor_slots):
+    """
+    Insert open plate slots and their compatible plates for a carrier item.
+    armor_slots: list of armorSlots from the API (only ItemArmorSlotOpen are relevant).
+    """
+    cursor = conn.cursor()
+    slot_count = 0
+    plate_count = 0
+    # Build set of known item IDs for fast lookup
+    known_ids = {row[0] for row in cursor.execute("SELECT id FROM gear_items").fetchall()}
+
+    for slot in armor_slots:
+        if slot.get("__typename") != "ItemArmorSlotOpen":
+            continue
+        slot_nameid = slot.get("nameId")
+        if not slot_nameid:
+            continue
+        zones = ",".join(slot.get("zones") or []) or None
+        cursor.execute("""
+            INSERT OR REPLACE INTO armor_open_slots (carrier_id, slot_nameid, zones)
+            VALUES (?, ?, ?)
+        """, (carrier_id, slot_nameid, zones))
+        slot_count += 1
+
+        for plate in (slot.get("allowedPlates") or []):
+            plate_id = plate.get("id")
+            if not plate_id or plate_id not in known_ids:
+                continue
+            cursor.execute("""
+                INSERT OR IGNORE INTO armor_slot_plates (carrier_id, slot_nameid, plate_id)
+                VALUES (?, ?, ?)
+            """, (carrier_id, slot_nameid, plate_id))
+            plate_count += 1
+
+    return slot_count, plate_count
+
+
 def import_suppressors(conn, items):
     cursor = conn.cursor()
     counts = {"inserted": 0, "updated": 0, "skipped": 0}
@@ -438,6 +536,7 @@ def main():
     rigs        = gear_data.get("rigs", [])
     suppressors = gear_data.get("suppressors", [])
     mods        = gear_data.get("mods", [])
+    plates      = gear_data.get("plates", [])
 
     # Wearables: only keep those whose properties resolved to ItemPropertiesHelmet
     # (i.e. they have 'class' or 'headZones' set — not decorative items)
@@ -451,7 +550,8 @@ def main():
         and (w["properties"].get("class") or w["properties"].get("headZones"))
     ]
     print(f"  armor={len(armor)}, helmets={len(helmets)}, wearable_helmets={len(wearable_helmets)}, "
-          f"backpacks={len(backpacks)}, rigs={len(rigs)}, suppressors={len(suppressors)}, mods={len(mods)}")
+          f"backpacks={len(backpacks)}, rigs={len(rigs)}, suppressors={len(suppressors)}, "
+          f"mods={len(mods)}, plates={len(plates)})")
 
     # Phase 2: insert into DB
     conn = sqlite3.connect(DB_PATH)
@@ -462,8 +562,12 @@ def main():
         wcounts, slot_data = import_weapons(conn, weapons)
         print(f"  guns:        +{wcounts['inserted']} inserted, ~{wcounts['updated']} updated, -{wcounts['skipped']} skipped")
 
+        print("Importing plates (armorPlate items)...")
+        c = import_plates(conn, plates)
+        print(f"  plates:      +{c['inserted']} inserted, ~{c['updated']} updated, -{c['skipped']} skipped")
+
         print("Importing armor...")
-        c = import_armor(conn, armor)
+        c, armor_slot_data = import_armor(conn, armor)
         print(f"  armor:       +{c['inserted']} inserted, ~{c['updated']} updated, -{c['skipped']} skipped")
 
         print("Importing helmets...")
@@ -479,7 +583,7 @@ def main():
         print(f"  backpacks:   +{c['inserted']} inserted, ~{c['updated']} updated, -{c['skipped']} skipped")
 
         print("Importing rigs...")
-        c = import_rigs(conn, rigs)
+        c, rig_slot_data = import_rigs(conn, rigs)
         print(f"  rigs:        +{c['inserted']} inserted, ~{c['updated']} updated, -{c['skipped']} skipped")
 
         print("Importing suppressors...")
@@ -496,6 +600,19 @@ def main():
         print(f"  gun_slots:      {slots_ins} rows")
         print(f"  gun_slot_items: {slot_items_ins} rows inserted, {slot_items_skip} skipped (item not in DB)")
 
+        # Phase 3b: armor open slots (needs plates in DB first)
+        print("Importing armor open plate slots...")
+        total_open_slots = 0
+        total_plate_links = 0
+        all_carrier_slots = {**armor_slot_data, **rig_slot_data}
+        for carrier_id, armor_slots in all_carrier_slots.items():
+            sc, pc = import_armor_open_slots(conn, carrier_id, armor_slots)
+            total_open_slots += sc
+            total_plate_links += pc
+        conn.commit()
+        print(f"  armor_open_slots: {total_open_slots} rows")
+        print(f"  armor_slot_plates: {total_plate_links} rows")
+
         # Phase 4: classify mod_type for mods based on which slots they appear in
         print("Classifying mod types from slot data...")
         cursor = conn.cursor()
diff --git a/migration_add_plates.sql b/migration_add_plates.sql
new file mode 100644
index 0000000..43876d5
--- /dev/null
+++ b/migration_add_plates.sql
@@ -0,0 +1,21 @@
+-- Migration: add armor plates support
+-- Run: sqlite3 tarkov.db < migration_add_plates.sql
+
+PRAGMA foreign_keys = ON;
+
+CREATE TABLE IF NOT EXISTS armor_open_slots (
+    carrier_id  TEXT NOT NULL REFERENCES gear_items(id) ON DELETE CASCADE,
+    slot_nameid TEXT NOT NULL,
+    zones       TEXT,
+    PRIMARY KEY (carrier_id, slot_nameid)
+);
+
+CREATE TABLE IF NOT EXISTS armor_slot_plates (
+    carrier_id  TEXT NOT NULL,
+    slot_nameid TEXT NOT NULL,
+    plate_id    TEXT NOT NULL REFERENCES gear_items(id) ON DELETE CASCADE,
+    PRIMARY KEY (carrier_id, slot_nameid, plate_id),
+    FOREIGN KEY (carrier_id, slot_nameid) REFERENCES armor_open_slots(carrier_id, slot_nameid) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_armor_slot_plates_plate ON armor_slot_plates(plate_id);
diff --git a/migrations_v2.sql b/migrations_v2.sql
index d1c9bf4..ebb9688 100644
--- a/migrations_v2.sql
+++ b/migrations_v2.sql
@@ -60,6 +60,26 @@ CREATE TABLE IF NOT EXISTS gun_slot_items (
 
 CREATE INDEX IF NOT EXISTS idx_gun_slot_items_item ON gun_slot_items(item_id);
 
+-- Open plate slots on armor/rig carriers (ItemArmorSlotOpen from tarkov API)
+-- Weight of a carrier does NOT include plates in these slots
+CREATE TABLE IF NOT EXISTS armor_open_slots (
+    carrier_id  TEXT NOT NULL REFERENCES gear_items(id) ON DELETE CASCADE,
+    slot_nameid TEXT NOT NULL,  -- e.g. "front_plate", "back_plate", "left_side_plate"
+    zones       TEXT,           -- comma-separated zone names e.g. "FR. PLATE,BCK. PLATE"
+    PRIMARY KEY (carrier_id, slot_nameid)
+);
+
+-- Which plates are compatible with each open slot on a carrier
+CREATE TABLE IF NOT EXISTS armor_slot_plates (
+    carrier_id  TEXT NOT NULL,
+    slot_nameid TEXT NOT NULL,
+    plate_id    TEXT NOT NULL REFERENCES gear_items(id) ON DELETE CASCADE,
+    PRIMARY KEY (carrier_id, slot_nameid, plate_id),
+    FOREIGN KEY (carrier_id, slot_nameid) REFERENCES armor_open_slots(carrier_id, slot_nameid) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_armor_slot_plates_plate ON armor_slot_plates(plate_id);
+
 -- Saved loadout builds
 CREATE TABLE IF NOT EXISTS saved_builds (
     id          INTEGER PRIMARY KEY AUTOINCREMENT,
diff --git a/tarkov.db b/tarkov.db
index b211171..3e8aef5 100644
Binary files a/tarkov.db and b/tarkov.db differ
diff --git a/templates/gun_detail.html b/templates/gun_detail.html
index f2e6e04..bcd78b0 100644
--- a/templates/gun_detail.html
+++ b/templates/gun_detail.html
@@ -197,106 +197,75 @@
   <div class="total-bar">
     <span class="lbl">Lightest possible build:</span>
     <span class="big">{{ "%.3f"|format(lightest_total) }} kg</span>
-    <span class="breakdown">base {{ "%.3f"|format(gun.weight_kg or 0) }} kg + lightest mod per slot</span>
+    <span class="breakdown">base {{ "%.3f"|format(gun.weight_kg or 0) }} kg + lightest mod per required slot</span>
   </div>
 
-  {% if key_slots %}
-  <div class="slot-section">
-    <div class="section-hdr">Key slots</div>
-    {% for slot in key_slots %}
-      {% set lightest = slot.mods[0] if slot.mods else none %}
-      <div class="slot-card key-slot {% if loop.first %}open{% endif %}" id="slot-{{ slot.slot_id }}">
-        <div class="slot-header" onclick="toggleSlot('slot-{{ slot.slot_id }}')">
-          <span class="slot-name">{{ slot.slot_name }}</span>
-          <span class="key-badge">key slot</span>
-          {% if slot.required %}<span class="required-badge">required</span>{% endif %}
-          <span class="slot-count">{{ slot.mods | length }} mods</span>
-          <span class="slot-lightest">
-            {% if lightest and lightest.weight_kg is not none %}
-              lightest {{ "%.3f"|format(lightest.weight_kg) }} kg
-            {% else %}—{% endif %}
-          </span>
-          <span class="chevron">▶</span>
-        </div>
-        <div class="mod-list">
-          {% if slot.mods %}
-            {% for mod in slot.mods %}
-            <div class="mod-row">
-              {% if mod.grid_image_url %}
-                <img src="{{ mod.grid_image_url }}" loading="lazy" alt="">
-              {% else %}
-                <div style="width:36px;height:36px;background:#222;border-radius:4px;flex-shrink:0"></div>
-              {% endif %}
-              <div class="mod-name">
-                {{ mod.mod_name }}
-                {% if mod.mod_short and mod.mod_short != mod.mod_name %}
-                  <small>{{ mod.mod_short }}</small>
-                {% endif %}
-              </div>
-              {% if mod.wiki_url %}
-                <a class="mod-wiki" href="{{ mod.wiki_url }}" target="_blank">wiki</a>
-              {% endif %}
-              <span class="mod-weight {% if loop.first %}lightest{% endif %}">
-                {% if mod.weight_kg is not none %}{{ "%.3f"|format(mod.weight_kg) }} kg{% else %}—{% endif %}
-              </span>
-            </div>
-            {% endfor %}
-          {% else %}
-            <div class="no-mods">No compatible mods found in database.</div>
-          {% endif %}
-        </div>
+  {# ---- Macro to render a slot card ---- #}
+  {% macro slot_card(slot, extra_class='', open=False) %}
+    {% set lightest = slot.mods[0] if slot.mods else none %}
+    <div class="slot-card {{ extra_class }} {% if open %}open{% endif %}" id="slot-{{ slot.slot_id }}">
+      <div class="slot-header" onclick="toggleSlot('slot-{{ slot.slot_id }}')">
+        <span class="slot-name">{{ slot.slot_name }}</span>
+        {% if extra_class == 'key-slot' %}<span class="key-badge">key slot</span>{% endif %}
+        <span class="slot-count">{{ slot.mods | length }} mods</span>
+        <span class="slot-lightest">
+          {% if lightest and lightest.weight_kg is not none %}
+            lightest {{ "%.3f"|format(lightest.weight_kg) }} kg
+          {% else %}—{% endif %}
+        </span>
+        <span class="chevron">▶</span>
       </div>
+      <div class="mod-list">
+        {% if slot.mods %}
+          {% for mod in slot.mods %}
+          <div class="mod-row">
+            {% if mod.grid_image_url %}
+              <img src="{{ mod.grid_image_url }}" loading="lazy" alt="">
+            {% else %}
+              <div style="width:36px;height:36px;background:#222;border-radius:4px;flex-shrink:0"></div>
+            {% endif %}
+            <div class="mod-name">
+              {{ mod.mod_name }}
+              {% if mod.mod_short and mod.mod_short != mod.mod_name %}
+                <small>{{ mod.mod_short }}</small>
+              {% endif %}
+            </div>
+            {% if mod.wiki_url %}
+              <a class="mod-wiki" href="{{ mod.wiki_url }}" target="_blank">wiki</a>
+            {% endif %}
+            <span class="mod-weight {% if loop.first %}lightest{% endif %}">
+              {% if mod.weight_kg is not none %}{{ "%.3f"|format(mod.weight_kg) }} kg{% else %}—{% endif %}
+            </span>
+          </div>
+          {% endfor %}
+        {% else %}
+          <div class="no-mods">No compatible mods found in database.</div>
+        {% endif %}
+      </div>
+    </div>
+  {% endmacro %}
+
+  {# ---- Required slots (key slots highlighted, open by default) ---- #}
+  {% if key_slots or req_slots %}
+  <div class="slot-section">
+    <div class="section-hdr">Required slots <span style="font-weight:normal;color:#666">(counted in lightest build weight)</span></div>
+    {% for slot in key_slots %}
+      {{ slot_card(slot, 'key-slot', open=True) }}
+    {% endfor %}
+    {% for slot in req_slots %}
+      {{ slot_card(slot, '', open=False) }}
     {% endfor %}
   </div>
   {% endif %}
 
-  {% if other_slots %}
-  <button class="toggle-other" onclick="toggleOther(this)">Show {{ other_slots | length }} other slots ▼</button>
+  {# ---- Optional slots (collapsed behind toggle) ---- #}
+  {% if optional_slots %}
+  <button class="toggle-other" onclick="toggleOther(this)">Show {{ optional_slots | length }} optional slots ▼</button>
   <div id="other-slots">
     <div class="slot-section">
-      <div class="section-hdr">All other slots</div>
-      {% for slot in other_slots %}
-        {% set lightest = slot.mods[0] if slot.mods else none %}
-        <div class="slot-card" id="slot-{{ slot.slot_id }}">
-          <div class="slot-header" onclick="toggleSlot('slot-{{ slot.slot_id }}')">
-            <span class="slot-name">{{ slot.slot_name }}</span>
-            {% if slot.required %}<span class="required-badge">required</span>{% endif %}
-            <span class="slot-count">{{ slot.mods | length }} mods</span>
-            <span class="slot-lightest">
-              {% if lightest and lightest.weight_kg is not none %}
-                lightest {{ "%.3f"|format(lightest.weight_kg) }} kg
-              {% else %}—{% endif %}
-            </span>
-            <span class="chevron">▶</span>
-          </div>
-          <div class="mod-list">
-            {% if slot.mods %}
-              {% for mod in slot.mods %}
-              <div class="mod-row">
-                {% if mod.grid_image_url %}
-                  <img src="{{ mod.grid_image_url }}" loading="lazy" alt="">
-                {% else %}
-                  <div style="width:36px;height:36px;background:#222;border-radius:4px;flex-shrink:0"></div>
-                {% endif %}
-                <div class="mod-name">
-                  {{ mod.mod_name }}
-                  {% if mod.mod_short and mod.mod_short != mod.mod_name %}
-                    <small>{{ mod.mod_short }}</small>
-                  {% endif %}
-                </div>
-                {% if mod.wiki_url %}
-                  <a class="mod-wiki" href="{{ mod.wiki_url }}" target="_blank">wiki</a>
-                {% endif %}
-                <span class="mod-weight {% if loop.first %}lightest{% endif %}">
-                  {% if mod.weight_kg is not none %}{{ "%.3f"|format(mod.weight_kg) }} kg{% else %}—{% endif %}
-                </span>
-              </div>
-              {% endfor %}
-            {% else %}
-              <div class="no-mods">No compatible mods found in database.</div>
-            {% endif %}
-          </div>
-        </div>
+      <div class="section-hdr">Optional slots <span style="font-weight:normal;color:#666">(not counted in lightest build weight)</span></div>
+      {% for slot in optional_slots %}
+        {{ slot_card(slot) }}
       {% endfor %}
     </div>
   </div>
@@ -311,8 +280,8 @@
     const div = document.getElementById('other-slots');
     div.classList.toggle('visible');
     btn.textContent = div.classList.contains('visible')
-      ? 'Hide other slots ▲'
-      : 'Show {{ other_slots | length }} other slots ▼';
+      ? 'Hide optional slots ▲'
+      : 'Show {{ optional_slots | length }} optional slots ▼';
   }
 </script>
 </body>
diff --git a/templates/loadout.html b/templates/loadout.html
index 9e5317f..8b927c2 100644
--- a/templates/loadout.html
+++ b/templates/loadout.html
@@ -231,7 +231,7 @@
   </p>
 
   <div class="tab-bar">
-    {% for t_id, t_label in [('guns','Guns'),('armor','Armor'),('helmets','Helmets'),('headwear','Headwear'),('backpacks','Backpacks'),('rigs','Rigs'),('builder','Build Builder')] %}
+    {% for t_id, t_label in [('guns','Guns'),('armor','Armor'),('helmets','Helmets'),('headwear','Headwear'),('backpacks','Backpacks'),('rigs','Rigs'),('plates','Plates'),('builder','Build Builder')] %}
       <a href="/loadout?tab={{ t_id }}" class="{% if tab == t_id %}active{% endif %}">{{ t_label }}</a>
     {% endfor %}
   </div>
@@ -328,6 +328,7 @@
       border-radius: 6px; padding: 5px 10px; font-size: 0.8rem; min-width: 110px;
     }
     .slot-pill.key { border-color: #5a7a3a; background: #141e10; }
+    .slot-pill.optional { opacity: 0.55; }
     .slot-pill .sp-name { color: var(--muted); font-size: 0.72rem; text-transform: uppercase; letter-spacing: 0.05em; }
     .slot-pill .sp-mod { font-size: 0.82rem; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; max-width: 150px; }
     .slot-pill .sp-w { color: var(--amber); font-size: 0.82rem; font-weight: bold; margin-top: 2px; }
@@ -382,23 +383,39 @@
       const baseCell = document.querySelector('[data-gun-id="' + gunId + '"] td:nth-child(6)');
       if (baseCell) baseWeight = parseFloat(baseCell.textContent) || 0;
 
+      // Only sum required slots for the lightest build weight
       let total = baseWeight;
-      let pills = '';
+      let reqPills = '';
+      let optPills = '';
       for (const s of slots) {
         const isKey = KEY.has(s.slot_nameid);
         const w = s.weight_kg != null ? s.weight_kg.toFixed(3) + ' kg' : '—';
-        if (s.weight_kg != null) total += s.weight_kg;
-        pills += `<div class="slot-pill${isKey ? ' key' : ''}">
-          <span class="sp-name">${s.slot_name}</span>
-          <span class="sp-mod">${s.mod_name || '—'}</span>
-          <span class="sp-w">${w}</span>
-        </div>`;
+        if (s.required) {
+          if (s.weight_kg != null) total += s.weight_kg;
+          reqPills += `<div class="slot-pill${isKey ? ' key' : ''}">
+            <span class="sp-name">${s.slot_name}</span>
+            <span class="sp-mod">${s.mod_name || '—'}</span>
+            <span class="sp-w">${w}</span>
+          </div>`;
+        } else {
+          optPills += `<div class="slot-pill optional">
+            <span class="sp-name">${s.slot_name}</span>
+            <span class="sp-mod">${s.mod_name || '—'}</span>
+            <span class="sp-w">${w}</span>
+          </div>`;
+        }
       }
 
+      const optSection = optPills
+        ? `<div style="font-size:0.75rem;color:var(--muted);text-transform:uppercase;letter-spacing:0.06em;margin:8px 0 4px">Optional slots (not included in weight)</div>
+           <div class="slot-summary">${optPills}</div>`
+        : '';
+
       inner.innerHTML = `
-        <div class="slot-summary">${pills}</div>
+        <div class="slot-summary">${reqPills || '<span style="color:var(--muted);font-size:0.82rem">No required slots</span>'}</div>
+        ${optSection}
         <div class="expand-footer">
-          <span class="expand-total">Lightest build: ${total.toFixed(3)} kg</span>
+          <span class="expand-total">Lightest build (required slots): ${total.toFixed(3)} kg</span>
           <a class="expand-link" href="/loadout/gun/${gunId}">Full breakdown →</a>
         </div>`;
     }
@@ -450,7 +467,10 @@
         <td class="muted">{{ item.durability | int if item.durability else '—' }}</td>
         <td class="muted">{{ item.material or '—' }}</td>
         <td class="muted" style="font-size:0.8rem">{{ item.zones or '—' }}</td>
-        <td class="w">{% if item.weight_kg is not none %}{{ "%.3f"|format(item.weight_kg) }} kg{% else %}—{% endif %}</td>
+        <td class="w">
+          {% if item.weight_kg is not none %}{{ "%.3f"|format(item.weight_kg) }} kg{% else %}—{% endif %}
+          {% if item.id in carrier_ids_with_open_slots %}<br><small class="muted">no plates</small>{% endif %}
+        </td>
       </tr>
     {% else %}
       <tr><td colspan="7" class="empty">No armor found.</td></tr>
@@ -653,7 +673,10 @@
         </td>
         <td class="muted">{{ item.capacity or '—' }}</td>
         <td class="muted" style="font-size:0.8rem">{{ item.zones or '—' }}</td>
-        <td class="w">{% if item.weight_kg is not none %}{{ "%.3f"|format(item.weight_kg) }} kg{% else %}—{% endif %}</td>
+        <td class="w">
+          {% if item.weight_kg is not none %}{{ "%.3f"|format(item.weight_kg) }} kg{% else %}—{% endif %}
+          {% if item.id in carrier_ids_with_open_slots %}<br><small class="muted">no plates</small>{% endif %}
+        </td>
       </tr>
     {% else %}
       <tr><td colspan="6" class="empty">No rigs found.</td></tr>
@@ -662,6 +685,63 @@
   </table>
   {% endif %}
 
+  {# =============================== PLATES TAB =============================== #}
+  {% if tab == "plates" %}
+  <p style="color:var(--muted);font-size:0.85rem;margin-bottom:12px;">
+    Armor plates that slot into plate carriers. Carrier shell weight does <em>not</em> include plates — add them separately when building your loadout.
+  </p>
+  <form method="get" class="filter-bar">
+    <input type="hidden" name="tab" value="plates">
+    <label>Min class</label>
+    <select name="min_class">
+      <option value="0" {% if min_class==0 %}selected{% endif %}>Any</option>
+      {% for c in range(1,7) %}
+        <option value="{{ c }}" {% if min_class==c %}selected{% endif %}>Class {{ c }}+</option>
+      {% endfor %}
+    </select>
+    <label>Sort</label>
+    <select name="sort">
+      <option value="weight_asc"  {% if sort=='weight_asc'  %}selected{% endif %}>Weight ↑</option>
+      <option value="weight_desc" {% if sort=='weight_desc' %}selected{% endif %}>Weight ↓</option>
+      <option value="class_desc"  {% if sort=='class_desc'  %}selected{% endif %}>Class ↓</option>
+      <option value="class_asc"   {% if sort=='class_asc'   %}selected{% endif %}>Class ↑</option>
+      <option value="name_asc"    {% if sort=='name_asc'    %}selected{% endif %}>Name A→Z</option>
+    </select>
+    <button type="submit">Filter</button>
+  </form>
+  <table class="gear-table">
+    <thead>
+      <tr>
+        <th></th><th>Name</th><th>Class</th>
+        <th>Durability</th><th>Material</th><th>Zones</th><th>Weight</th>
+      </tr>
+    </thead>
+    <tbody>
+    {% for item in plates %}
+      <tr>
+        <td>{% if item.grid_image_url %}<img src="{{ item.grid_image_url }}" loading="lazy" alt="">{% endif %}</td>
+        <td class="name-cell">
+          <strong>{{ item.short_name or item.name }}</strong>
+          {% if item.short_name and item.short_name != item.name %}<small>{{ item.name }}</small>{% endif %}
+          {% if item.wiki_url %}<a href="{{ item.wiki_url }}" target="_blank" style="font-size:0.78rem;margin-left:4px">wiki</a>{% endif %}
+        </td>
+        <td>
+          {% if item.armor_class %}
+            <span class="cls cls-{{ item.armor_class }}">{{ item.armor_class }}</span>
+          {% else %}—{% endif %}
+        </td>
+        <td class="muted">{{ item.durability | int if item.durability else '—' }}</td>
+        <td class="muted">{{ item.material or '—' }}</td>
+        <td class="muted" style="font-size:0.8rem">{{ item.zones or '—' }}</td>
+        <td class="w">{% if item.weight_kg is not none %}{{ "%.3f"|format(item.weight_kg) }} kg{% else %}—{% endif %}</td>
+      </tr>
+    {% else %}
+      <tr><td colspan="7" class="empty">No plates found.</td></tr>
+    {% endfor %}
+    </tbody>
+  </table>
+  {% endif %}
+
   {# =============================== BUILD BUILDER TAB =============================== #}
   {% if tab == "builder" %}
   <script>
@@ -671,6 +751,15 @@
       {% endfor %}
     };
 
+    // carriers that have open plate slots (shell weight only)
+    const CARRIERS_WITH_OPEN_SLOTS = new Set({{ carrier_ids_with_open_slots | list | tojson }});
+
+    // plate weight cache: id -> weight_kg
+    const PLATE_WEIGHTS = {};
+
+    // currently selected plate weights per open slot, keyed by "carrierSlot|slotNameId"
+    const _plateSlotWeights = {};
+
     function recalcWeight() {
       const slots = ['gun', 'armor', 'helmet', 'rig', 'backpack'];
       let total = 0;
@@ -679,12 +768,85 @@
         const id = sel ? sel.value : '';
         const w = id ? (WEIGHTS[id] || 0) : 0;
         const disp = document.getElementById('sw_' + slot);
-        if (disp) disp.textContent = id ? w.toFixed(3) + ' kg' : '';
+        if (disp) {
+          if (id) {
+            const isCarrier = CARRIERS_WITH_OPEN_SLOTS.has(id);
+            disp.textContent = w.toFixed(3) + ' kg' + (isCarrier ? ' (shell only)' : '');
+          } else {
+            disp.textContent = '';
+          }
+        }
         total += w;
       }
+      // Add plate weights
+      for (const pw of Object.values(_plateSlotWeights)) {
+        total += pw;
+      }
       document.getElementById('total-weight').textContent = total.toFixed(3);
     }
 
+    const _carrierSlotCache = {};
+
+    function onCarrierChange(slot) {
+      const sel = document.getElementById('slot_' + slot);
+      const carrierId = sel ? sel.value : '';
+      const container = document.getElementById('plates_' + slot);
+      container.innerHTML = '';
+      // Clear plate slot weights for this carrier slot
+      for (const key of Object.keys(_plateSlotWeights)) {
+        if (key.startsWith(slot + '|')) delete _plateSlotWeights[key];
+      }
+      if (!carrierId || !CARRIERS_WITH_OPEN_SLOTS.has(carrierId)) {
+        recalcWeight();
+        return;
+      }
+      if (_carrierSlotCache[carrierId]) {
+        renderPlateSlots(slot, carrierId, _carrierSlotCache[carrierId]);
+        return;
+      }
+      fetch('/loadout/carrier/' + carrierId + '/slots.json')
+        .then(r => r.json())
+        .then(data => {
+          _carrierSlotCache[carrierId] = data;
+          renderPlateSlots(slot, carrierId, data);
+        });
+    }
+
+    function renderPlateSlots(carrierSlot, carrierId, slots) {
+      const container = document.getElementById('plates_' + carrierSlot);
+      container.innerHTML = '';
+      for (const slot of slots) {
+        const key = carrierSlot + '|' + slot.slot_nameid;
+        const label = document.createElement('label');
+        label.style.cssText = 'display:block;margin-top:8px;font-size:0.82rem;color:var(--muted)';
+        label.textContent = slot.slot_nameid.replace(/_/g, ' ') + (slot.zones ? ' (' + slot.zones + ')' : '');
+        const sel = document.createElement('select');
+        sel.style.cssText = 'width:100%;margin-top:2px';
+        const none = document.createElement('option');
+        none.value = '';
+        none.textContent = '— No plate —';
+        sel.appendChild(none);
+        for (const p of slot.plates) {
+          PLATE_WEIGHTS[p.id] = p.weight_kg || 0;
+          const opt = document.createElement('option');
+          opt.value = p.id;
+          opt.textContent = (p.short_name || p.name) +
+            ' (Cls ' + (p.armor_class || '?') + ', ' +
+            (p.weight_kg != null ? p.weight_kg.toFixed(3) : '?') + ' kg)';
+          sel.appendChild(opt);
+        }
+        sel.addEventListener('change', () => {
+          const pid = sel.value;
+          _plateSlotWeights[key] = pid ? (PLATE_WEIGHTS[pid] || 0) : 0;
+          recalcWeight();
+        });
+        container.appendChild(label);
+        container.appendChild(sel);
+        _plateSlotWeights[key] = 0;
+      }
+      recalcWeight();
+    }
+
     function saveBuild() {
       const slots = ['gun', 'armor', 'helmet', 'rig', 'backpack'];
       const payload = { name: document.getElementById('build-name').value.trim() || 'My Build' };
@@ -714,24 +876,25 @@
 
   <div class="builder-grid">
     {% set slot_defs = [
-      ('gun',      'Primary Weapon', builder_guns),
-      ('armor',    'Body Armor',     builder_armor),
-      ('helmet',   'Helmet',         builder_helmets),
-      ('rig',      'Chest Rig',      builder_rigs),
-      ('backpack', 'Backpack',       builder_backpacks),
+      ('gun',      'Primary Weapon', builder_guns,      false),
+      ('armor',    'Body Armor',     builder_armor,     true),
+      ('helmet',   'Helmet',         builder_helmets,   false),
+      ('rig',      'Chest Rig',      builder_rigs,      true),
+      ('backpack', 'Backpack',       builder_backpacks, false),
     ] %}
-    {% for slot_id, slot_label, items in slot_defs %}
+    {% for slot_id, slot_label, items, has_plates in slot_defs %}
     <div class="slot-card">
       <h3>{{ slot_label }}</h3>
-      <select id="slot_{{ slot_id }}" onchange="recalcWeight()">
+      <select id="slot_{{ slot_id }}" onchange="{% if has_plates %}onCarrierChange('{{ slot_id }}'){% else %}recalcWeight(){% endif %}">
         <option value="">— None —</option>
         {% for item in items %}
           <option value="{{ item.id }}">
-            {{ item.name }}{% if item.weight_kg is not none %} ({{ "%.3f"|format(item.weight_kg) }} kg){% endif %}
+            {{ item.name }}{% if item.weight_kg is not none %} ({{ "%.3f"|format(item.weight_kg) }} kg{% if item.id in carrier_ids_with_open_slots %} shell{% endif %}){% endif %}
           </option>
         {% endfor %}
       </select>
       <div class="slot-weight" id="sw_{{ slot_id }}"></div>
+      {% if has_plates %}<div id="plates_{{ slot_id }}"></div>{% endif %}
     </div>
     {% endfor %}
   </div>