79c88f1b_de___Payment_Service_SDK___1_8__Description
[Field] SKU [Description] 
This field specifies the SKU that you can use to identify the digital goods that you sell in an application. When a user initiates purchases of digital goods from within your application, the Payment Service server can use the SKU to identify the digital goods. If you want to use one SKU to identify multiple digital goods, you can differentiate between the digital goods by invoking the withMetadata() purchase argument in your application.
Add digital goods to an application - Development Guide - Payment Service SDK - 1.8