The tool steel extractors have a left-hand threaded spiral flute designed for extra gripping power. The drill bits are made of high-speed steel for high hardness which can drill through most screws. This set is designed to remove damaged or stripped screws, bolts, fasteners. Easy to use, first drill a hole in the center of the broken screw with the appropriate drill bit, then use an appropriate extractor to remove the screw. Comes with a tap handle that can hold the extractor firmly; for the large extractor, you can use an adjustable wrench. Product Description Specifications: Material: HHS (drill bits), tool steel (extractors) Suitable screws (for reference only): #1 for M3~M3.5 #2 for M4~M4.5 #3 for M5~M7 #4 for M8~M9 #5 for M10~M12 Drill bit diameters: 2.0mm, 3.0mm, 4.0mm, 6.5mm, 7.5mm Features: This set is designed to remove damaged or stripped screws, bolts, and fasteners. The drill bits are made of high-speed steel for high hardness which can drill through most screws. The tool steel extractors have a left-hand threaded spiral flute designed for extra gripping power. Easy to use, first drill a hole in the center of the broken screw with the appropriate drill bit, then use an appropriate extractor to remove the screw. Comes with a tap handle that can hold the extractor firmly; for the large extractor, you can use an adjustable wrench. Package includes: 1 x Broken Screw Extractor Set