The original Lifehammer emergency tool has an extra-tough double-ended hammer to break panes of vehicle glass. For car windows, bus windows, etc, you need this window breaker. The ultra-sharp, protected safety blade will cut through a seat belt without being dangerous to fingers.

And, if you think you won't be able to find it in an emergency, it not only has a mounting bracket but also has a photoluminescent, glow-in-the-dark button

This hammer is for vehicles and is not suitable for domestic or commercial double-glazing. See the Lifeaxe instead