Feature: 1. Durable: Made of strong M35 high speed steel and added with 5% cobalt to form a hardened heat resistant alloy, with faster cutting speed and longer service life 2. Accurate Positioning: 118 ° X shaped opening design for more accurate positioning and effectively reduce bit slip 3. Hex Shank Design: Hex handle design, not easy to slip, more firm and more durable 4. Application: Can drill 2mm thin iron (hardness within 25 degrees), 2mm copper plate or aluminum plate, 5mm wood plate or plastic plate 5. Specification : The diameter of the handle is 6.35mm, and the diameter of 4mm, 6mm, 8mm, 10mm and 12mm can be drilled Specification: Item Type: Spiral Step Drill Bit Material: High Speed Steel Cover Treatment: Titanize Handle Type: Hex Handle Handle Diameter: Approx. 6.35mm / 0.3in Drillable Diameter (mm): Approx. 4mm / 0.2in Approx. 6mm / 0.23in Approx. 8mm / 0.31in Approx. 10mm / 0.4in Approx. 12mm / 0.5in Drillable Thickness: Approx. 2mm / 0.08in Thin Iron (Hardness within 25°) Approx. 2mm / 0.08in Copper Plate or Aluminum Plate Approx. 5mm / 0.2in Wood Plate or Plastic Angle: 118° . Package List: 1 x Spiral Step Drill Bit Note: Please allow 0 to 2 cm error due to manual measurement. Thanks for your understanding.