diff --git a/core/ShopState.lua b/core/ShopState.lua
index c530ffb..4655462 100644
--- a/core/ShopState.lua
+++ b/core/ShopState.lua
@@ -97,10 +97,15 @@
 
 local function handlePurchase(transaction, meta, sentMetaname, transactionCurrency, transactionCurrency, state)
     local purchasedProduct = nil
-    for _, product in ipairs(state.products) do
-        if product.address:lower() == sentMetaname:lower() or product.name:gsub(" ", ""):lower() == sentMetaname:lower() then
-            purchasedProduct = product
-            break
+    if state.eventHooks and state.eventHooks.preProduct then
+        purchasedProduct = eventHook.execute(state.eventHooks.preProduct, transaction, transactionCurrency, meta, sentMetaname, state.products)
+    end
+    if purchasedProduct == nil then
+        for _, product in ipairs(state.products) do
+            if product.address:lower() == sentMetaname:lower() or product.name:gsub(" ", ""):lower() == sentMetaname:lower() then
+                purchasedProduct = product
+                break
+            end
         end
     end
     if purchasedProduct then
@@ -295,7 +300,11 @@
         end
     end, function()
         while state.running do
-            ScanInventory.updateProductInventory(state.products)
+            local onInventoryRefresh = nil
+            if state.eventHooks and state.eventHooks.onInventoryRefresh then
+                onInventoryRefresh = state.eventHooks.onInventoryRefresh
+            end
+            ScanInventory.updateProductInventory(state.products, onInventoryRefresh)
             if state.config.settings.hideUnavailableProducts then
                 state.productsChanged = true
             end
diff --git a/core/inventory/ScanInventory.lua b/core/inventory/ScanInventory.lua
index 8ae47d0..b8ecca3 100644
--- a/core/inventory/ScanInventory.lua
+++ b/core/inventory/ScanInventory.lua
@@ -1,3 +1,5 @@
+local eventHook = require("util.eventHook")
+
 local itemCache = {}
 
 local partialObjectMatches
@@ -128,7 +130,7 @@
     return items
 end
 
-local function updateProductInventory(products)
+local function updateProductInventory(products, onInventoryRefresh)
     for i = 1, #products do
         products[i].newQty = 0
     end
@@ -140,6 +142,9 @@
         product.quantity = product.newQty
         product.newQty = nil
     end
+    if onInventoryRefresh then
+        eventHook.execute(onInventoryRefresh, products, items)
+    end
 end
 
 local function getItemCache()
diff --git a/core/schemas.lua b/core/schemas.lua
index 8a6c0bd..28c3da5 100644
--- a/core/schemas.lua
+++ b/core/schemas.lua
@@ -218,6 +218,7 @@
         name = "string?",
         address = "string",
         category = "string?",
+        hidden = "boolean?",
         price = "number",
         priceOverrides = {
             __type = "array?",
diff --git a/eventHooks.lua b/eventHooks.lua
index 67f336b..56b6933 100644
--- a/eventHooks.lua
+++ b/eventHooks.lua
@@ -1,5 +1,8 @@
 return {
     start = nil, -- function(version, config, products)
+    preProduct = nil, -- function(transaction, transactionCurrency, meta, productAddress, products) returns product
+    -- If product is nil, product will be selected by the shop,
+    -- If product is false, customer will be refunded for no product found.
     prePurchase = nil, -- function(product, amount, refundAmount, transaction, transactionCurrency) returns continueTransaction, error, errorMessage
     purchase = nil, -- function(product, amount, refundAmount, transaction, transactionCurrency)
     failedPurchase = nil, -- function(transaction, transactionCurrency, product, errorMessage)
@@ -7,4 +10,5 @@
     blink = nil, -- function(blinkState) called every 3 seconds while shop is running
     configSaved = nil, -- function(config) called when config is edited (replaced)
     productsSaved = nil, -- function(products) called when products object is edited (replaced)
+    onInventoryRefresh = nil, -- function(products, items) called when inventory is refreshed, product quantity can be set through products table
 }
\ No newline at end of file
diff --git a/products.lua b/products.lua
index ce11724..dc5f839 100644
--- a/products.lua
+++ b/products.lua
@@ -31,5 +31,12 @@
                 }
             }
         }
+    },
+    {
+        modid = "minecraft:barrier",
+        name = "Secret item",
+        address = "secret",
+        hidden = true,
+        price = 1.0
     }
 }
\ No newline at end of file
diff --git a/radon.lua b/radon.lua
index 6fdeee9..cd01fb8 100644
--- a/radon.lua
+++ b/radon.lua
@@ -1,4 +1,4 @@
-local version = "1.3.14"
+local version = "1.3.15"
 local configHelpers = require "util.configHelpers"
 local schemas       = require "core.schemas"
 local oldPullEvent = os.pullEvent
diff --git a/util/renderHelpers.lua b/util/renderHelpers.lua
index 303f1ea..54b74bc 100644
--- a/util/renderHelpers.lua
+++ b/util/renderHelpers.lua
@@ -37,27 +37,29 @@
 local function getCategories(products)
     local categories = {}
     for _, product in ipairs(products) do
-        local category = product.category
-        if not category then
-            category = "*"
-        end
-        local found = nil
-        for i = 1, #categories do
-            if categories[i].name == category then
-                found = i
-                break
+        if not product.hidden then
+            local category = product.category
+            if not category then
+                category = "*"
             end
-        end
-        if not found then
-            if category == "*" then
-                table.insert(categories, 1, {name=category, products={}})
-                found = 1
-            else
-                table.insert(categories, {name=category, products={}})
-                found = #categories
+            local found = nil
+            for i = 1, #categories do
+                if categories[i].name == category then
+                    found = i
+                    break
+                end
             end
+            if not found then
+                if category == "*" then
+                    table.insert(categories, 1, {name=category, products={}})
+                    found = 1
+                else
+                    table.insert(categories, {name=category, products={}})
+                    found = #categories
+                end
+            end
+            table.insert(categories[found].products, product)
         end
-        table.insert(categories[found].products, product)
     end
     return categories
 end