diff --git a/Block/Checkout/Onepage/Success.php b/Block/Checkout/Onepage/Success.php
index b0d9159..dce89af 100644
--- a/Block/Checkout/Onepage/Success.php
+++ b/Block/Checkout/Onepage/Success.php
@@ -1,33 +1,58 @@
-<?php declare(strict_types=1);
+<?php
 
 /**
  * Copyright © Itonomy BV. All rights reserved.
  * See LICENSE.md for license details.
  */
-
 namespace Itonomy\Flowbox\Block\Checkout\Onepage;
 
+use Itonomy\Flowbox\Helper\Data;
+use Magento\Checkout\Model\Session;
+use Magento\Cookie\Helper\Cookie;
+use Magento\Framework\Encryption\EncryptorInterface;
+use Magento\Framework\View\Element\Template\Context;
+use Magento\Catalog\Model\ProductRepository;
+
 class Success extends \Itonomy\Flowbox\Block\Base
 {
-    private \Magento\Checkout\Model\Session $checkoutSession;
+    /**
+     * @var Session
+     */
+    private $checkoutSession;
+
+    /**
+     * @var Data
+     */
+    private $helper;
+
+    /**
+     * @var ProductRepository
+     */
+    private $productRepository;
 
     /**
      * Success constructor.
-     * @param \Magento\Framework\View\Element\Template\Context $context
-     * @param \Magento\Framework\Encryption\EncryptorInterface $encryptor
-     * @param \Magento\Cookie\Helper\Cookie $cookie
-     * @param \Magento\Checkout\Model\Session $checkoutSession
+     * @param Context $context
+     * @param EncryptorInterface $encryptor
+     * @param Cookie $cookie
+     * @param Session $checkoutSession
+     * @param ProductRepository $productRepository
+     * @param Data $helper
      * @param array $data
      */
     public function __construct(
-        \Magento\Framework\View\Element\Template\Context $context,
-        \Magento\Framework\Encryption\EncryptorInterface $encryptor,
-        \Magento\Cookie\Helper\Cookie $cookie,
-        \Magento\Checkout\Model\Session $checkoutSession,
+        Context $context,
+        EncryptorInterface $encryptor,
+        Cookie $cookie,
+        Session $checkoutSession,
+        ProductRepository $productRepository,
+        Data $helper,
         array $data = []
     ) {
         parent::__construct($context, $cookie, $encryptor, $data);
+        $this->helper = $helper;
         $this->checkoutSession = $checkoutSession;
+        $this->productRepository = $productRepository;
     }
 
     /**
@@ -38,15 +63,17 @@ protected function prepareConfig(): void
         try {
             $order = $this->checkoutSession->getLastRealOrder();
 
+
             $this->setData('flowbox', [
                 'allowCookies' => $this->isUserAllowSaveCookies(),
                 'apiKey' => (string) $this->getApiKey(),
                 'debug' => $this->isDebugJavaScript(),
                 'orderId' => \ltrim($order->getIncrementId(), '#'),
                 'products' => \array_map(
-                    function ($item) {
+                    function ($item){
+                        $product = $this->productRepository->get($item->getSku());
                         return [
-                            'id' => (string) $item->getSku(),
+                            'id' => (string) $product->getData($this->helper->getAttributeCode()),
                             'quantity' => (int) $item->getQtyOrdered()
                         ];
                     },
diff --git a/Helper/Data.php b/Helper/Data.php
new file mode 100644
index 0000000..7675b91
--- /dev/null
+++ b/Helper/Data.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace Itonomy\Flowbox\Helper;
+
+use Magento\Framework\App\Helper\AbstractHelper;
+use Magento\Framework\App\Config\ScopeConfigInterface;
+use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Store\Model\ScopeInterface;
+use Magento\Store\Model\StoreManagerInterface;
+
+class Data extends AbstractHelper
+{
+    /**
+     * @var ScopeConfigInterface
+     */
+    protected $scopeConfig;
+
+    /**
+     * @var StoreManagerInterface
+     */
+    protected $storeManager;
+
+    /**
+     * @param ScopeConfigInterface $scopeConfig
+     * @param StoreManagerInterface $storeManager
+     */
+    public function __construct(
+        ScopeConfigInterface $scopeConfig,
+        StoreManagerInterface $storeManager
+    ) {
+        $this->scopeConfig = $scopeConfig;
+        $this->storeManager = $storeManager;
+    }
+
+    /**
+     * @return string
+     * @throws NoSuchEntityException
+     */
+    public function getAttributeCode(): string
+    {
+        return $this->scopeConfig->getValue(
+            'itonomy_flowbox/general/checkout_identifier',
+            ScopeInterface::SCOPE_STORE,
+            $this->storeManager->getStore()->getId()
+        );
+    }
+}
diff --git a/Model/Config/Source/CheckoutIdentifier.php b/Model/Config/Source/CheckoutIdentifier.php
new file mode 100644
index 0000000..4991149
--- /dev/null
+++ b/Model/Config/Source/CheckoutIdentifier.php
@@ -0,0 +1,63 @@
+<?php
+
+
+namespace Itonomy\Flowbox\Model\Config\Source;
+
+use Magento\Eav\Model\ResourceModel\Entity\Attribute\Collection;
+use Magento\Framework\Data\OptionSourceInterface;
+
+
+class CheckoutIdentifier implements OptionSourceInterface
+{
+    /**
+     * @var Collection
+     */
+    private $collection;
+
+
+    /**
+     * @param Collection $collection
+     */
+    public function __construct(
+        Collection $collection
+    )
+    {
+        $this->collection = $collection;
+    }
+
+    /**
+     * @return array
+     */
+    public function getUniqueAttributes(): array
+    {
+        $collection = $this->collection;
+
+        $collection->addFieldToFilter(
+            'entity_type_id',
+            ['eq' => '4']
+        );
+        $collection->addFieldToFilter(
+            'is_unique',
+            ['eq' => '1']
+        );
+        return $collection->toArray();
+    }
+
+    /**
+     * @return array
+     */
+    public function toOptionArray(): array
+    {
+        $items = $this->getUniqueAttributes();
+        $options = [];
+
+        if (array_key_exists('items', $items)) {
+            foreach ($items['items'] as $item) {
+                $options[] = ['value' => $item['attribute_code'],
+                    'label' => $item['frontend_label']
+                ];
+            }
+        }
+        return $options;
+    }
+}
diff --git a/etc/adminhtml/system.xml b/etc/adminhtml/system.xml
index fc942cf..f161064 100644
--- a/etc/adminhtml/system.xml
+++ b/etc/adminhtml/system.xml
@@ -28,6 +28,11 @@
                     <comment>Your Flowbox API key</comment>
                     <backend_model>Magento\Config\Model\Config\Backend\Encrypted</backend_model>
                 </field>
+                <field id="checkout_identifier" type="select" translate="label comment" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1" canRestore="1">
+                    <label>Checkout Identifier</label>
+                    <source_model>Itonomy\Flowbox\Model\Config\Source\CheckoutIdentifier</source_model>
+                    <comment>Select the product identifier for the checkout script</comment>
+                </field>
             </group>
         </section>
     </system>
diff --git a/etc/config.xml b/etc/config.xml
index c9e8453..fef5acf 100644
--- a/etc/config.xml
+++ b/etc/config.xml
@@ -12,6 +12,7 @@
             <general>
                 <enable>1</enable>
                 <debug_javascript>0</debug_javascript>
+                <checkout_identifier>sku</checkout_identifier>
             </general>
         </itonomy_flowbox>
         <dev>