High-quality high-speed steel spiral step drill bit with strong durability and long service life. The drill bit is hardened and polished for sharp cutting edges. The two-slot design helps material chips escape, enabling cleaner drilling. Shank and dimensions - Nitrided triangular shank with a diameter of 10 mm - Total length: 100 mm - Weight: 230 g Set contents and sizes - This nitrided triangular shank spiral groove step drill set includes three ranges: - 12 mm range: sizes 4 mm, 6 mm, 8 mm, 10 mm, 12 mm - Bit #2 (9 steps): 4-20 mm range with sizes 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm - Bit #3 (15 steps): 4-32 mm range with sizes 4 mm, 6 mm, 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, 32 mm Applications and suitability - Wide application range: ideal for drilling holes in various materials - Suitable for drilling holes in iron plates up to 2 mm (0.12 inch) thick, copper plates, aluminum plates, as well as wood, PVC sheets, and insulation boards - Not suitable for hard and brittle materials such as stainless steel, glass, tile floors, walls, etc. Key benefits - Durable high-speed steel construction with hardened, polished edges for long life and reliable cutting - Efficient debris removal with a two-slot design to reduce binding and provide cleaner holes - Rigid nitrided triangular shank improves grip and reduces slippage in the chuck - Compact, multi-size ranges cover common hole sizes from 4 mm to 32 mm in three stepped configurations Use scenarios - Drywall and metal cabinet fabrication: create clean holes in thin iron, copper, or aluminum plates up to 2 mm thick - Electrical and plumbing work: size holes for conduits or cables in metal sheets and wooden or PVC panels - DIY projects and home renovation: prepare holes in wood, PVC sheets, and insulation boards for fittings and fixtures Notes - For best results, use with appropriate drill speed and lubrication as needed - Do not attempt to drill hard or brittle materials such as stainless steel, glass, tile, or dense masonry with this set