When a vehicle encounters an emergency, the safety hammer is pointed at the side window of the car, and the hidden collision needle is released by pressing its buttock hard. The collision needle breaks the window glass instantaneously, and then the collision needle automatically returns to its position. It can be used repeatedly as a ballpoint pen. But because of the impact of the pin, it is better to use magazines and other things to pad it in order to avoid being damaged by broken glass. It takes about 8 kilograms of power to activate this button, and almost everyone can press it.