Various SizesThere are total 5 different size extractors for screws with diameter from 4mm to 18mm. The steel tool pullers have a left-handed spiral flute designed for extra gripping power. Aggressive left handed (extractors) and right handed (drill bits) spiral flute design for extra gripping power. Design ConceptThis set is designed for removing screws, bolts, fasteners , damaged, rusty or bare metal water tap and water tube etc. High QualityThe drill bits are made of high speed steel for high hardness which can drill on most screws. The drill bits can also be used to drill holes on wood, metal, plastic, brick and wall, etc. Easy to UseDrill a hole in the center of the broken screw first with a suitable drill, then use a suitable extractor to remove the screws. Drill diameters and recommended extraction diameters of broken screws are engraved on the case