Features of industrial impact sockets are greater wall thickness for resisting impact loads, special heat treatment for toughness and strength, a black industrial finish and the cross hole retaining feature. Impact sockets are available in 1/4 inch to 2 1/ 2 inch square drives from 6mm to 160mm across flat of Nut/Bolt. (1/4 to 6 1/4 inch SAE). Caution : These sockets are for use with impact wrenches. Eye protection should always be used while using impact equipment.