8740 A HF. 1/4″ drive for Hex (Allen head) socket bolts/screws. These socket bits come with holding function and Hex- Plus bits, offering a larger tool to bolt contact to prevent bolt damage. Compatible with all hex (Allen head) bolts. Chrome vanadium with a brushed chrome plated finish and color coded for finding the right size quickly. Knurled at the base for easier manual turning. With ball intercept ring. Overall length is mentioned in millimeters. Note: Not compatible with impact wrenches. Size: 5/16″. Overall Length: 28mm.