Life saving emergency Mini Car Window Glass Breaker & Escape Tool
That device will allow you to cut the seat belt and break the car's window in case of an emergency.
Keep that keychain with your car keys so that in case of an emergency all you have to do is pull the buckle out and cut the seat belt quickly.
If needed, put the device near the window's corner and press it vigorously, the window will be broken and you will be able to get out of the car.
Size: 75 x 35 x 15mm/2.95 x 1.37 x 0.59in