[Step Drill Bit Size]: 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm. A variety of drill bits can meet your different needs, saving time and money. [Premium Materials]: These step drill bits are made of heat-treated 4241 high-speed steel (HSS) and coated with titanium nitride. The titanium coating can reduce friction and operating temperature, which can effectively extend the service life. [Stepped Structure]: The drill bit can drill holes of different specifications without the need to purchase multiple drill bits, saving space and money. [Double Groove]: Automatic deburring when drilling. Cutting is faster and smoother. Three flat handles ensure a firm grip. Triangular round shank: can be easily installed in electric screwdriver, drill bit and press drill. [Applicable]: The step drill bit set can be used for workpieces with hardness less than 25° and thickness less than 5mm. Suitable for various materials, such as carbon steel, iron sheet, insulation board, PVC board, wood board