Rounded off head. Bought a 5 pc set of special sockets for $25 @ Autozone. Did not notice the 15mm was used until I got home. Called the phone on the receipt. Store manager said I could return the set. I asked him if I could use the 13mm and then return the set. He said no, "You use it, you keep it." I replied "Why? Someone else used it and returned it and you put it back on the shelf. I'm sorry. OK, I'll bring it back now for a refund but I live near Elmendorf so it'll take me about 25 minutes to get to the store. Oh. Go ahead and use the 13 and then bring it back and I'll help you out. I was offended at that comment but everything worked out in the end. Stores shouldn't put expensive used tools back on the shelf. It took four attempts with the special tool, removing more material each time, but it did work. And the store manager did give me my money back.