Product IDs and Variants
The core of identifying orders, returns and size recommendations through the Faslet flow is about making sure the Product IDs and SKUs are consistent all the way through. This is why we ask for a Product ID and SKU to be sent through at every step of the flow.
A Good Product ID
It doesn't really matter what the Product ID you send Faslet is, what matters is that it's the same on a product page, and in the order tracking. On product pages, Faslet uses this to identify what sizing to use, so we don't recommend using variant identifiers (such as a GTIN or SKU) here. We recommend using the same ID as you would for the Item Group ID in a Google shopping feed. This is often called a Product ID, Product Group ID, or Product Parent ID.
SKUs
It is important to send through SKUs with the variants, as well as the orders and returns. This allows us to track specific items that are returned and determine the whether the sizing matched Faslet's recommendations. For analytics purposes, we can then use this to provide insights on an SKU level for things such as return percentages and missed sales.
Variant IDs and Add-to-Cart
Variant IDs are important for the add-to-cart functionality. Depending on your platform, these are required to be the platform's identifiers, but for custom platforms, we simply pass through the selected Variant ID to the add-to-cart function. Since the Variant ID is given to us in the Size Me Up Virtual Assistant setup, this can be whatever you require for add-to-cart to work on your platform.
Example
For a concrete example of how the SKUs, Product IDs and variants map to each other, see our documentation on Variants and Add-to-cart.