Unlike eBay or craigslist, items on Amazon are listed under fixed, pre-existing products, with variations (in condition, included accessories, etc.) noted in its comments field. On a baseline seller account, it's not even possible to create a listing for a new item that doesn't already exist on Amazon.com.

So I found an X220 listing with different specs, and noted the specs of mine in the comments. The other two used listings had done the same.