Feature: 1. These drill bits are made of ti plated high speed steel, which has high hardness and good wear resistance, and is not easy to deform. 2. The step drill bit adopts 118 X shape opening design, which can effectively prevent slippage, and the double straight grooves make drilling and chip removal are smoother. 3. The serrated drill bit adopts a 35 inclined blade design, which can be used for horizontal sawing after drilling. 4. The step drill is standard 1/4in hex shank, and the serrated drill is 3mm, 6mm and 8mm round shank, suitable for various equipment. 5. These drills are suitable for drilling, grooving and cutting on thin wood, aluminum, and plastic boards and other materials. Specification: Item Type: Step Drill Bits Material: High speed steel Purpose: Suitable for drilling, grooving and cutting of thin wood, aluminum alloy and plastic boards Barb Bit Shank Type: Hex shank(1/4in) Barb Bit Specifications: Approx. 4-12mm / 0.2-0.5in, 4-20mm / 0.2-0.8in, 4-30mm / 0.2-1.2in Serrated Drill Shank Type: Round shank (3mm 6mm 8mm) Serrated Drill Specifications: Approx. 3mm / 0.12in, 6mm / 0.24in, 8mm / 0.31in . Package List: 3 x Step Drill Bits3 x Serrated Drill Bits 1 x Storage Box Note: The product is made of metal, please do not place the product in an environment that is too corrosive, humid and high temperature