Made of high- materials, durable The drill is made of heat-treated and tempered carbon steel, which has cutting force and durability, and accuracy is higher than of drills. The countersunk head has an automatic starting , and the -slot design eliminates chatter and vibration, and makes the operation , thereby achieving clean, and burr-free cutting. You can drill the screw hole and counterbore of the nut at the same time, and keep the two on the same axis. After tightening the nut, the nut is located the plane of the circuit board. The standard 1/4-inch hex handle can be quickly replaced, and the depth of the second sleeve can be adjusted by covering the matching plug with a flat-head screw head Hex key or a cover. Eject wood , you can a surface on any type of hard, cork or aluminum. Suitable for workpieces with hardness lower than 25HRC, such as carbon steel, thin iron plate, insulating plate, PVC plate, wood board, etc. Colour:Black+silver Material:Carbon steel Size:countersunk drills: 5#/6#/8#/10#/12# Package Contents: 4 x claw corkscrews 4 x barrel cork drills 5 x countersunk drills 1 x wrench Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.