IRWIN Tools IMPACT Performance Series Fastener Power Bits, 17-Piece Set with Pro Case and Magnetic Screw-Hold Attachment (1903768) IMPACT performance series bits are designed specifically for impact drivers and the higher torque they produce. Precision tip geometry delivers superior fitment, reducing stripping and cam-out and increasing the life of bit and fasteners. Heavy-duty, cold-forged, high-grade steel withstands high torque. The black oxide finish resists corrosion and increases the life of the bit. Magnetic screw-hold attachment's low-profile collar attaches easily to PowerGroove on bits and holds fasteners securely, reducing wobbling and slip. Molded ABS resin case with metal hinge holds up to rigors of daily use. 2-step easy in / out storage holds bits securely in place until you need them.