My 96 Silverado had some pretty badly stripped and corroded exhaust head pipe flange bolts (See pic).The previous owner tired to fix the exhaust leak and stripped the bolts. I gave one of these sockets a try and it worked! This is something every mechanic must have.

After fighting a rounded off bolt for two days and trying every trick in the book without any success I found this item online. It worked exactly the way it was described. Took less than 15 seconds to take off a completely rounded bolt that had been over torqued with that red lock-tite stuff on it. It' has become my best tool in the box.