Fits hex size: 9mm 10mm 11mm 12mm 13mm 14mm 15mm 16mm 17mm 19mm 10pc Nut Bolt Extractor Socket comes with Metal Box The specially hardened sockets with corrosion protection are designed for the removal of damaged bolts, screws and nuts. The spiral 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