Proto J5100: Designed for easy torque calibrations. Adapters measure 2\" from the center of the square drive to the center of the adapter opening. Special heat-treated alloy steel helps to increase strength and durability. Box end wall thickness is specifically designed to provide strength while still allowing ample room for access to reach difficult fasteners. Reduced risk of fastener rounding. Sockets apply more torque to fastener .Includes:3/8\". 7/16\". 1/2\". 9/16\". 5/8\". 11/16\". 3/4\". 13/16\". 7/8\". (1) Socket bar., Lot of 1