Different product attributes same SKU I need the user to choose a serial number from a drop down when viewing the product display. For example there is a product SKU of unxm_12 for Uncanny Xmen #12, there are 3 in stock and each one has a serial number, all are the same price. 

We want the user to be able to choose a serial number from a drop down and then we can view that serial number on the order later to determine which comic book they actually want.

This needs to be custom for each product, each SKU can have multiple serial numbers. There are many products. What is the best way to do this?
Have you tried Commerce Product Attributes?