It is best to use electric hand drill, can not be used the hammer drill mode Striped screw extractor removes even the most stubborn stripped, damaged, embedded, rusted and painted-over screws and bolts Higher hardness and is more than most screw extractors in market, the hardness and the durability are better 4 pieces screw extractors work with any drill and all the screw size or bolt These extractor tools are used to reverse the damaged screw counterclockwise until it is released Use a suitable size screw remover to drill a hole with cutting size and it ’ s easy to extract the screw or bolt using extractor tool, Manufacturer: yanwuwa