Impact socket bit sets come with an assortment of bit sizes to tighten and loosen fasteners. Impact bits have a bit on one end that fits the head of the fastener while the opposite end of the bit has a square drive that attaches to an impact power wrench with the same drive size. Impact power wrenches can provide more torque to the head of a fastener than a hand wrench and the impact socket bits can handle the higher torque and vibration generated by an impact power wrench when loosening and tightening fasteners.