diff --git a/src/graphics/ui/elements/InventoryView.cpp b/src/graphics/ui/elements/InventoryView.cpp
index 78e56e78..9c180e2e 100644
--- a/src/graphics/ui/elements/InventoryView.cpp
+++ b/src/graphics/ui/elements/InventoryView.cpp
@@ -186,17 +186,26 @@ void SlotView::draw(const DrawContext& pctx, const Assets& assets) {
         }
     }
 
-    if (stack.getCount() > 1) {
+    if (stack.getCount() > 1 || stack.getFields() != nullptr) {
         auto font = assets.get<Font>("normal");
-        std::wstring text = std::to_wstring(stack.getCount());
+        
+        if (stack.getCount() > 1) {
+            std::wstring text = std::to_wstring(stack.getCount());
 
-        int x = pos.x+slotSize-text.length()*8;
-        int y = pos.y+slotSize-16;
+            int x = pos.x+slotSize-text.length()*8;
+            int y = pos.y+slotSize-16;
 
-        batch->setColor({0, 0, 0, 1.0f});
-        font->draw(*batch, text, x+1, y+1, nullptr, 0);
-        batch->setColor(glm::vec4(1.0f));
-        font->draw(*batch, text, x, y, nullptr, 0);
+            batch->setColor({0, 0, 0, 1.0f});
+            font->draw(*batch, text, x+1, y+1, nullptr, 0);
+            batch->setColor(glm::vec4(1.0f));
+            font->draw(*batch, text, x, y, nullptr, 0);
+        }
+        if (stack.getFields() != nullptr) {
+            batch->setColor({0, 0, 0, 1.0f});
+            font->draw(*batch, L"#", pos.x+1, pos.y+1, nullptr, 0);
+            batch->setColor(glm::vec4(1.0f));
+            font->draw(*batch, L"#", pos.x, pos.y, nullptr, 0);
+        }
     }
 }
 
diff --git a/src/items/Inventory.cpp b/src/items/Inventory.cpp
index 1d27e261..5978f283 100644
--- a/src/items/Inventory.cpp
+++ b/src/items/Inventory.cpp
@@ -72,8 +72,12 @@ void Inventory::deserialize(const dv::value& src) {
         if (item.has("count")){
             count = item["count"].asInteger();
         }
+        dv::value fields = nullptr;
+        if (item.has("fields")) {
+            fields = item["fields"];
+        }
         auto& slot = slots[i];
-        slot.set(ItemStack(id, count));
+        slot.set(ItemStack(id, count, fields));
     }
 }
 
@@ -92,6 +96,10 @@ dv::value Inventory::serialize() const {
         if (count) {
             slotmap["count"] = count;
         }
+        const auto& fields = item.getFields();
+        if (fields != nullptr) {
+            slotmap["fields"] = fields;
+        }
     }
     return map;
 }
@@ -110,5 +118,3 @@ void Inventory::convert(dv::value& data, const ContentReport* report) {
     inventory.convert(report);
     data = inventory.serialize();
 }
-
-const size_t Inventory::npos = -1;
diff --git a/src/items/Inventory.hpp b/src/items/Inventory.hpp
index f0efdfe1..29205640 100644
--- a/src/items/Inventory.hpp
+++ b/src/items/Inventory.hpp
@@ -26,10 +26,6 @@ public:
         itemid_t id, size_t begin = 0, size_t end = -1, size_t minCount = 1
     );
 
-    inline size_t size() const {
-        return slots.size();
-    }
-
     void move(
         ItemStack& item,
         const ContentIndices& indices,
@@ -46,17 +42,21 @@ public:
     void convert(const ContentReport* report);
     static void convert(dv::value& data, const ContentReport* report);
 
-    inline void setId(int64_t id) {
+    size_t size() const {
+        return slots.size();
+    }
+
+    void setId(int64_t id) {
         this->id = id;
     }
 
-    inline int64_t getId() const {
+    int64_t getId() const {
         return id;
     }
 
-    inline bool isVirtual() const {
+    bool isVirtual() const {
         return id < 0;
     }
 
-    static const size_t npos;
+    static constexpr size_t npos = -1;
 };
diff --git a/src/items/ItemStack.cpp b/src/items/ItemStack.cpp
index fdf1ff80..3e63371a 100644
--- a/src/items/ItemStack.cpp
+++ b/src/items/ItemStack.cpp
@@ -3,13 +3,18 @@
 #include "content/Content.hpp"
 #include "ItemDef.hpp"
 
-ItemStack::ItemStack(itemid_t item, itemcount_t count)
-    : item(item), count(count) {
+ItemStack::ItemStack(itemid_t item, itemcount_t count, dv::value data)
+    : item(item), count(count), fields(std::move(data)) {
 }
 
 void ItemStack::set(const ItemStack& item) {
+    set(ItemStack(item));
+}
+
+void ItemStack::set(ItemStack&& item) {
     this->item = item.item;
     this->count = item.count;
+    this->fields = std::move(item.fields);
     if (count == 0) {
         this->item = 0;
     }
@@ -22,14 +27,14 @@ bool ItemStack::accepts(const ItemStack& other) const {
     if (isEmpty()) {
         return true;
     }
-    return item == other.getItemId();
+    return item == other.getItemId() && other.fields == nullptr;
 }
 
 void ItemStack::move(ItemStack& item, const ContentIndices& indices) {
     auto& def = indices.items.require(item.getItemId());
     itemcount_t count = std::min(item.count, def.stackSize - this->count);
     if (isEmpty()) {
-        set(ItemStack(item.getItemId(), count));
+        set(ItemStack(item.getItemId(), count, std::move(item.fields)));
     } else {
         setCount(this->count + count);
     }
@@ -39,6 +44,27 @@ void ItemStack::move(ItemStack& item, const ContentIndices& indices) {
 void ItemStack::setCount(itemcount_t count) {
     this->count = count;
     if (count == 0) {
-        item = 0;
+        clear();
     }
 }
+
+void ItemStack::setField(std::string_view name, dv::value value) {
+    if (fields == nullptr) {
+        if (value == nullptr) {
+            return;
+        }
+        fields = dv::object();
+    }
+    if (value == nullptr) {
+        fields.erase(std::string(name));
+        return;
+    }
+    fields[std::string(name)] = std::move(value);
+}
+
+dv::value* ItemStack::getField(const std::string& name) const {
+    if (fields == nullptr) {
+        return nullptr;
+    }
+    return fields.at(name).ptr;
+}
diff --git a/src/items/ItemStack.hpp b/src/items/ItemStack.hpp
index e2892bf3..c7ff7e0c 100644
--- a/src/items/ItemStack.hpp
+++ b/src/items/ItemStack.hpp
@@ -2,20 +2,31 @@
 
 #include "constants.hpp"
 #include "typedefs.hpp"
+#include "data/dv.hpp"
 
 class ContentIndices;
 
 class ItemStack {
     itemid_t item = ITEM_EMPTY;
     itemcount_t count = 0;
+    dv::value fields = nullptr;
 public:
     ItemStack() = default;
 
-    ItemStack(itemid_t item, itemcount_t count);
+    ItemStack(itemid_t item, itemcount_t count, dv::value data=nullptr);
 
     void set(const ItemStack& item);
+    void set(ItemStack&& item);
     void setCount(itemcount_t count);
 
+    /// @brief Set a field in the item stack data.
+    void setField(std::string_view name, dv::value value);
+
+    /// @brief Get a field from the item stack data.
+    /// @param name field name
+    /// @return value pointer or nullptr if the field does not exist.
+    dv::value* getField(const std::string& name) const;
+
     bool accepts(const ItemStack& item) const;
 
     /// @brief Move items from one stack to another. 
@@ -24,19 +35,23 @@ public:
     /// @param indices content indices
     void move(ItemStack& item, const ContentIndices& indices);
 
-    inline void clear() {
+    void clear() {
         set(ItemStack(0, 0));
     }
 
-    inline bool isEmpty() const {
+    bool isEmpty() const {
         return item == ITEM_EMPTY;
     }
 
-    inline itemid_t getItemId() const {
+    itemid_t getItemId() const {
         return item;
     }
 
-    inline itemcount_t getCount() const {
+    itemcount_t getCount() const {
         return count;
     }
+
+    const dv::value& getFields() const {
+        return fields;
+    }
 };