Milwaukee's 48-32-1551 42-Piece S2 Impact Duty Driver Bit Set is engineered for extreme durability and up to ten times a longer life. Made from proprietary steel and heat treated to control hardness, these Impact Duty Driver Bits feature an innovatively designed geometric shock absorption zone to extend life. The forged tip allows for a secure grip and maximum contact, eliminating stripping or slipping. This set offers a variety of driver bits for everyday use as well as rare applications. Made of premium grade S2 tool steel, this 48-32-1151 set is heavy duty, designed for hard use.