LEXPON 4PCS Screw Extractor Double Side Damaged Out Remover Bolt Stud Tool Material:HSS(4341) Handle:Hexagon handle 1/4''(6.35mm) The screw head be damaged thicker than extractor , with the drilling head end drill a hole( deep enough) in the middle of the screw head. Reverse screw extractor and into the damaged screw counterclockwise, until removed. Note:Operation or in the vicinity of electric tools, please wear glasses boxes and protective clothing.