The Lisle 8-pc Double-Ended Hex/Twist Socket Set, No. 13420, features a double-ended design with a 6-point hex on one side and a left-hand twist spiral with sharp edges on the other side that firmly bites stripped nuts without slipping. The impact-rated sockets are made of chrome-moly steel and come organized in a molded case. The set includes a 3" long 1/2" drive extension and sizes 17mm, 18mm, 19mm, 21mm, 22mm, 24mm, and 27mm.