Impact socket bits come with a tool bit on one end that fits the indentation in the fastener head to tighten or loosen fasteners. The opposite end of the socket 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 can handle the high torque and vibration generated by an impact power wrench when loosening and tightening fasteners.