High Quality Materials: Made of high quality HSS, titanium coating ensures extreme durability, reduces friction and heat. Easy to drill: Mark hole locations and design two-flute design makes drilling faster and smoother. Surface depth gauges make drilling accurate. Lifetime: High-speed steel step drill design. Through heat treatment and tempering, so 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 5 mm to 35 mm in diameter, optimal speed and precision. You can achieve large hole processing, no need to replace the drill bit and positioning hole. Wide Usage: Suitable for sheet metal, sink, car repair, etc. Widely used to cut holes in a variety of material like plate, aluminum, insulation board, PVC board, wood thickness within 5mm.