[Step Drill Size]: 5-35mm(5mm , 7mm ,10mm ,12mm ,15mm ,17mm ,20mm ,22mm ,25mm ,27mm ,30mm ,32mm ,35mm). 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 titanium nitride coated. The titanium coating can reduce friction and operating temperature, which can effectively extend the service life. [Ladder structure]: The drill bit can drill holes of different specifications without purchasing multiple drill bits, saving space and money. [Double Groove]: Automatic deburring when drilling. Faster and smoother cutting. Three flat handles ensure a firm grip. Triangular round shank: can be easily installed in electric screwdriver, drill bit and pressure drill. [Applies to]: The step drill bit set can be used for workpieces of hardness less than 25 and less than 5 mm thick. Suitable for various materials, such as carbon steel, iron sheet, insulation board, PVC board, wooden board and wood, etc. They also help to enlarge existing holes and are not recommended for stainless steel. Features: Color: Gold. Material: High Speed Steel 4241. Surface: Titanium Plated. Stem Type: Triangular Round Handle. Stem Size: 23 x 12mm. Size: 5-35mm (5,7,10,12,15,17,20,22,25,27,30,32,35mm). Usage: 5mm material thickness. Package Contents: 1 Step Drill Bit 5-35mm (Gold).