【Material】Mark a starting point with metal pins (steel, aluminum, brass, copper), wood, glass, leather or plastic and prevent drills or screws from slipping. 【Adjustable】The automatic center punch has a built-in spring to adjust the tension, you can adjust the lid clockwise or counterclockwise to get it just right and hold very well 【Wild Application】The automatic center punch can be used as a manual punching tool on wood, soft metal, glass;it can also be used to break car windows to allow you to escape in an emergency 【Easy to Use】: Simple one-handed operation without a hammer.Anyone who only has one hand available for hitting will not want to do without this tool.You will find that self-punching punches are a good addition to the home tool kit. 【Specifications】The metal grain is 128 mm (5.04 inches) long and 11 mm (0.49 inches) in diameter.Set contains two automatic center punches and two replacement punches.The exterior shape is compact and easy to carry