Features undercut flutes for more positive grip. Each extractor has the size stamped on it. Heat treated for traditional strength. Tempered tapping ends prevents chipping. Made in the USA 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".