MIBRO 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. Pack includes two 1-inch Star/Torx #25 insert bits. *