Industrial Grade Step Drill HSS-CO M35 Cobalt. This listing is for a step drill with a 4mm to 32mm range. It can drill through stainless steel sheets, which cheaper step drills (4241 high-speed steel) cannot. We also sell 4mm-22mm, 5mm-21mm, and 4mm-12mm sizes. This is a high-grade step drill, but we can sell it at a low price because we source it directly from the manufacturing factory. This product is from a company that focuses on manufacturing step drills and has strict quality control. They primarily sell to the Japanese export market. They likely have transactions with Amazon vendors and major online shopping site sellers. The step drill in this listing is a cobalt-coated high-speed steel step drill. Step drills sold in sets of 3 at low prices are usually 4241 high-speed steel with titanium coating, which is inferior to cobalt coating in terms of coating grade. Hole sizes: φ4/6/8/10/12/14/16/18/20/22/24/26/28/30/32 (mm) Material: Cobalt-coated high-speed steel Drilling capacity: Stainless steel sheet: 2mm Iron plate: 4mm 6.35mm hex shank We have also included comparison images using this product and a cheaper step drill. The images are of the 4mm-22mm product, but the performance is equivalent. We used 3mm stainless steel sheets for the photos, but 2mm is recommended. It can drill through 3mm without any problems, but please be careful as it may put a load on the drill's shaft depending on the model used. It gradually enlarges the hole size from small to large, so you can drill, enlarge, and modify holes of various sizes. The spiral shape is ideal for stainless steel and is suitable for drilling holes in stainless steel, thin iron plates, aluminum plates, wood, vinyl, and resin. You can process without cutting oil, but we recommend applying cutting oil for long-term use. A rust inhibitor is applied to the drill to prevent rust. Shipping method is standard mail. DIY / Electric drill / Power tool / Hex shank / Attachment / Carpenter's tools / Bicycle / Automobile / Maintenance / Attachment / 18V / 14.4V / Makita / Hitachi / MAX