Universal socket was designed to automatically adjust to fit any nut or bolt from 7-19 mm (1/4 inches to 3/4 inches). Works with various shapes of screws, nuts, hooks, lag screws, eye screws, bolt heads and even broken, stripped and rusted nuts. Product Features Includes a 3/8" power adapter for electric drill or screwdriver 54 steel pins automatically adjusts to any shape Technical Data Size Range: 7 - 19 mm / 1/4 - 3/4 in. Socket Length: 52 mm Drive Size: 3/8 inch Drive Type: Square Material: Chrome Vanadium Steel