7-piece power bolt grip set. Grips both metric and SAE - Universal Lobular Design fits both sizes. Black oxide finish with white markings - prevents rust and easy-to-read markings. Maximum gripping power - reverse spiral flutes are designed to bite down. Removes rounded off, painted over, damaged, and rusted over nuts and bolts. Shear-resistant shank - high-carbon steel shank is larger than most fastener shanks and resists torsional shear. 1/4" hex shank for use with cordless drills, impact drivers, corded drills, and nut runners. Power groove allows for use with quick change adapters. Includes sizes: 3/16", 1/4", 5/16", 3/8", 10mm, 7/16", 1/2", and plastic case.