> For the complete documentation index, see [llms.txt](https://docs.optis.me/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.optis.me/product-options/advanced-setup/how-to-use-upsell-product-link-stock-and-price-of-shopify-variant-to-option-value.md).
# How to Use "Upsell product"? Link Stock and Price of Shopify Variant to Option Value
Our app supports **product option inventory management**, allowing specific options to be **grayed out when out of stock** and ensuring that inventory updates automatically when a customer purchases an option.
This feature, called **"Upsell product"** links an option to a specific Shopify variant, syncing stock and price automatically. This feature is available in our **$19.99/month plan**:
### Step-by-Step Guide to Set Up "Upsell product"
#### Step 1: Create Draft Products with Variants
1. In your Shopify store, create a draft product with different variants.
2. Assign stock levels and prices to each variant.
* Example:
* **Black variant:** Stock = **5**, Price = **$0** (only tracks stock).
* **White variant:** Stock = **0**, Price = **$1000** (tracks both stock and price).
#### Step 2: Assign Variants to Product Options
1. Navigate to the **Upsell product** section in the app.
2. Select the corresponding Shopify variant for each option.
#### Step 3: View the Result on Your Storefront
* If a variant is out of stock, the assigned option will be **grayed out** automatically.
* If a variant has stock (for example 4 stocks), then the option linked with this variant will also have 4 stocks
* When a customer purchases an option, the inventory updates in real-time (e.g., black stock reduces from 5 to 4).
#### **Optional: Keep Variants in Draft Mode**
* If you do not want these variants to appear as active products in your store, you can keep them in **draft mode** in Shopify.
By following these steps, you can **prevent customers from selecting out-of-stock options** while keeping your inventory automatically updated!
