If you’re going to test the window breaker on a car glass window, be sure to wear safety gloves and goggles. Alternatively, you can test the window breaker on a hard surface like a notepad or a piece of wood. When the spring-loaded spike is released, you will hear a “click.” After you lift up the tool again, another spring resets the spike so you can use it again. You will see a small dent where the tip of the spike met the testing surface. The seatbelt cutter blade is very sharp and will easily cut through seatbelts. Hold the seatbelt tape taut and pull the tool toward you, cutting it diagonally.