Five-piece base set is made of high-carbon steel. Reverse spiral flutes are designed to bite down to provide maximum gripping power. Universal lobular design fits all types of fasteners. 3/8 in square drive for use with hand ratchets, impact wrenches, air ratchets, hexagonal flats for use with flat wrench, pliers, adjustable wrench, sockets or VISE-GRIP locking pliers. Includes 3/8 in, 7/16 in (11 mm), 1/2 in, 9/16 in (14 mm) and 5/8 in (16 mm) bolt grips.
