Description:1. "X" shaped holes, drilling is not easy to slip. Higher precision, sharper, no burrs.2. Unique step structure, the drill bit can drill a variety of hole sizes. You can deburr, chamfer, punch elliptical hole.3. Suitable for installation in pistol drill and bench drill.4. Hardness of the workpiece below 25° below, such as iron, aluminum, pvc board, insulation board, wood, workpiece thickness 4mm.5. The surface of high-speed steel is coated with titanium to achieve higher hardness and wear resistance. Specifications:Material: 4241 high speed steel Surface treatment: titanium plating Step drill bit: 4-12/4-20/4-32mm Drill bits: 3/6/8mmPackage included:6pcs without box or 6pcs per box (as shown in the picture)Note:1. Please allow 1-3cm differs due to manual measurement.2. Due to the different display and different light, the picture may not show the actual color of the item. Thank you for your understanding.