ACE screwdriver bits are premium, professional-grade power tool accessories. Made to exacting standards, these bits will not let you down. All bits are made from premium S2 tool steel. They are heat-treated and tempered to achieve an optimal hardness of 58-62 HRC, which will absorb shock, reduce twisting and cam-out, while not stripping screw heads. Size tolerances are tightly controlled to ensure consistent and accurate fit. Double-ended bits are a convenient and versatile option for DIY users. Paqck includes six 2-inch bits with 12 assorted bit types and sizes. The most popular types are represented: Phillips, Square Recess, Slot and Star (Torx) * Double-ended screwdriver bits combine two heads in a durable one-piece design for added convenience and versatilityBits include: Star #15/#20, Square Recess #1/#2, Phillips #1/#2, Phillips #2/Square #2, Phillips #1/Slot #6-8, Phillips #2/Slot #8-102 in. bit lengthProfessional-grade power tool accessory made from premium S2 tool steelHeat-treated and tempered S2 steel absorbs shock, resists twisting and cam-out for superior tool lifeTorque-balanced to reduce breakageManufactured for precise fit in the fastener's head1/4 in. hex shank fits in all bit holders6 pieces included