I came across this at Home Depot today and had to buy it. It's a set of sockets for
rounded off, painted over or rusted or damaged bolts and nuts. The inside looks like a reversed EZ-out. They're claimed to be strong enough to use with an impact wrench. It's made by the company that makes Vise-grips. I'm going to go out and find a screwed up bolt or nut on one of my junkers tomorrow and try them out.