Removes broken studs, set screws, pipe and alemite fittings. It's simple to use, just drill a hole in the screw and place extractor in the hole. Tap lightly with hammer and turn counterclockwise with tap wrench to remove the screw. This set includes the following screw extractors: 1/4" and 5/16", 3/8", 7/16", 1/2" and 9/16", 5/8".