High Quality Step Drill Bits: HSS tapered drill bits are made of high speed steel (4241), which drills through the hardest materials to reduce heat and frictional cooling and automatically removes deposits from the holes during drilling, very durable. The spiral design prevents slippage and makes drilling easier. Nitrogen-filled high speed steel spiral flute drill bits are of better quality than ordinary step drill bits. Unique Design: The spiral groove ensures optimal chip removal. The numbering of each step accurately indicates the drilling diameter in mm. Compared with ordinary twist drill bits, you can use an automatic center punch that is not easy to break. This allows for more precise drilling, increased efficiency and less breakage. The tapered drill bit gives a very good visual impression. Multi-purpose: Perfect for home DIY and general construction/mechanical engineering. It is suitable for drilling holes in a variety of materials, including stainless steel, wood, thin