Heavy duty power impact sockets are specially designed for use with all types of power wrenches. All sockets are hot forged from the finest alloy steels for maximum strength and durability. Heat treated by carefully controlled methods, the sockets are accurately broached in 6 point openings. All power impact sockets are finished in rust resistant black oxide. Made in U.S.A. 3-7/8" Type III opening. 6 Points standard. 3-1/4" Drive end, 5-1/2" opening end, 1-59/64" minimum depth, 5-1/4" overall length.