11pc Nut Bolt Extractor Socket And Tommy bar Set The specially hardened sockets with corrosion protection are designed for the removal of damaged bolts, screws and nuts. The Twist socket design allows for a secure connection onto the rounded-off fastener to be extracted. The innovative spiral profile digs itself into the head of a damaged screw or nut, allowing it to be easily loosened. 3/8" square drive for use with socket wrench or impact wrench. These broken bolt extractors have Black oxide surface provides greater strength and durability and prevents corrosion.