The set is intended for unscrewing and cleaning broken screws. It helps a lot when the situation seems hopeless. Types of extractors in the package: 0# (2.0-2.4mm) 1# (2.5-2.8mm) 2# (3.2-3.4mm) 3# (3.8-4.0mm) 4# (5.2-6.0mm) Material : steel 4341 Instruction : Select the appropriate size extractor for the screw/pin you wish to remove. On the side of the drill, drill a hole in the broken screw/pin by turning it clockwise. Turn the extractor so that you can use the extraction side. Set the tool to rotate counter-clockwise and start removing the broken screw. WARNING! Start very slowly, do not increase speed or use extra force.