High Quality Materials: Made of high quality HSS, the titanium coating ensures extreme durability, reduces friction and heat. Easy to Drill: Mark hole locations and the dual flute design makes drilling faster and smoother. Surface depth gauges make drilling precise. Lifespan: High speed steel step drill bit design. By heat treatment and tempering, therefore, the step bits have the function of long-term use. HSS Professional Step Drill Bit: Unique design of high speed steel professional step drill bit for precise drilling of various hole sizes from 5mm to 35mm in diameter, optimum speed and precision. You can get big hole treatment, no need to replace the drill and positioning hole. Wide use: Suitable for sheet metal, sink, car repair, etc. Widely used for cutting holes in a variety of material like plate, aluminum, insulation board, PVC board, wood thickness within 5mm. Features: - Durable and high quality HSS steel with titanium coating, titanium coating to reduce friction and heat. - With only need a small amount of pressure and automatically deburr holes when drilling. - Provides fast, smooth and clean cuts, each step is clearly labeled with the depth diameter. - Widely used for cutting holes in a variety of materials such as steel, wood, fine iron, aluminum alloy, insulation board, PVC sheet, etc. Specification: Material: High speed steel Color: gold Models: 5-35mm Hole size: 5mm, 7mm, 10mm, 12mm, 15mm, 17mm, 20mm, 22mm, 25mm, 27mm, 30mm, 32mm, 35mm (13 steps) Package included: 1 x Conical Drill Tips: Recommended drilling speed: 250400 rpm. It is made of HSS-4241 stainless steel. Suitable for use with hardness less than 25 HRC, plate thickness less than 5mm. Refreshes the water while working, it can effectively extend the service life. Warning: 1.Remember to protect your hands when using it. 2.This product is not sold to children.