A SKU (stock keeping unit) is a specific merchant's product identifier. The SKU is a critical piece of data in every inventory file that you submit to us. Amazon uses the SKUs in your inventory file to associate your products with the appropriate product detail page in our catalog (if one already exists). This means the following:
- Every product in your inventory file must have a unique SKU.
- Up to 40 one-byte alphanumeric characters can be entered.
- An existing SKU cannot be changed; it remains in the catalog until you delete it. That is, you cannot change SKU "123" so that it reads "ABC" in our system simply by changing the SKU in your inventory file.
- If you upload an inventory file with data for a SKU that already exists, the more recent data replaces data from previous feeds.
For more details on the role of SKUs in your inventory, see Build My Inventory File.