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 irwin impact performance series magnetic screw hold attachment this set contains the following7 x phillips bits ph1 x 2 ph2 x 4 a