eBay Private Seller stating "No Returns"

RHemmings

It's impossible to know exactly how the fault is distributed between the buyer and the seller in this case as we don't know how specific 'XXX' is. I can see why the OP is reluctant to say what XXX is, there has already been one implied threat by a poster on here about being able to find the OP's ebay account.

However, I vote for a return being the correct action here. The seller didn't describe the product properly as they didn't say what versions of XXX the item was compatible with. It's true that the OP could have defended his/herself better by further research, but IMHO this does not move all of the responsibility from the seller to the buyer. Depending on what XXX is will affect the proportion of the fault that would be distributed between the seller and the buyer. But, the seller didn't describe the item properly, and hence a return is justified.