High speed steel co M35 step drill bits, higher quality and more durable than HSS 4241 step drill bits. High speed cobalt steel together with titanium coating ensure extreme durability, it will stay looking new and shiny for years to come. Hex Shank Diameter: 6.35mm. No need for center punch, compared with ordinary twist drill bit, it is not easy to break, and it can be used for deburring, chamfering and opening hole. High speed steel co M35 step drill bit, from higher quality and more durable than the HSS 4241 step drill. Effective as an excellent cobalt drill. Made of super tough HSS steel for extra durability and longer life. Non-walking drill tip provides fast, smooth drills on steel plate, aluminum sheet, wooden boards, plastic boards, etc. (The board should be smaller in thickness than the height of the step drills). Size:4-20mm Features: < p> Material: High Speed Steel, Co (HSS co M35) Surface Treatment: Titanium Coated Hex Shank Diameter: 6.35mm / 1/4" Dimension: 4-20mm (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm);9 steps Features: Titanium coating to reduce mit and heat. High speed steel co M35 step drill bit, better quality and more durable than HSS 4241 step drill bit Punch Effective as an excellent cobalt drill bit. Very useful for drilling and especially drilling holes in stainless steel, metals, plastics and wood. Suitable for drilling holes in sheet metal, steel plate, aluminum plate, brass or wood Highly recommended tool to have in the workshop About Trepanning for stainless steel sheets: 1. Hand drill and bench drill can be used when trepanning stainless steel sheet, hand drill steel sheet within 1mm, and bench drill can drill a 2-3 mm steel sheet 2. It is necessary to drill at low speed when trepanning stainless steel sheets, hundreds of rpm are fine. 3. Please water it for cooling during punching to prolong its service life, 250-400 rotation rate is recommended. Note: -At trephination, please wear good protective measures, in case of wood chip splash. -Size for manual measurement, there may be 0-3mm error, belongs to the normal phenomenon. -The knife is quite sharp, keep away from children. -Due to the difference between different monitors, the picture may not reflect the actual color of the 'item. Package List: 1 * Co M35 Hex Shank Step Drill Bit