To check which package is pair with a specific product you have 2 options:
The first is to visit PRODUCTS>PACKAGING, select the correct item, and click on the MANAGE button. Select the specific customization of that package and click on settings. Here you will see all the product pair with a specific package.
On the other side, you visit PRODUCT, find your item and click on manage. On this page, you will see the packages pair with that specific products.