The Irwin Impact Screwdriver Bits are specifically designed for use in high torque impact drivers. They are manufactured from heavy-duty, high-grade steel and have a 3 times increased life compared to standard screwdriver bits. Their precision tip geometry delivers superior fitment, reducing stripping and cam-out. The bits are Power Groove designed for compatibility with the IRWIN® Impact Performance Series™ magnetic screw-hold attachment. This set contains the following:4 x PH2 screwdriver bits.1 x Magnetic screw hold attachment. Supplied in a moulded ABS resin case.