Undercut edges provide solid grip in broken screws, bolts, studs, pipes, and zerk fittings Chrome Molybdenum steel extractors for the toughest applications Patented design eliminates the need to drill a hole before extracting screw Coarse threads bite into screw and loosen it with each blow of impact driver Fits JET impact drivers and competitors models with 5/16 in-drive bit adapter Heat-treated SAE6150 chrome vanadium steel withstands repeated use