If you carry a full size flashlight, like the Streamlight 20X, the cap alone will not break glass. There is no way you can break a window with these flashlights without causing damage to your expensive light or injuring someone from flying glass.  Attaching Bust A Cap® to your flashlight will insure that it will break glass with just one tap and not damage your equipment.

This cap is unique to the Streamlight 20X because it has a spring that you must remove from the old cap and put on your new Bust A Cap. 

Warning: Please remove the o-rings from the old cap and put on your new Bust a cap to insure that your light remains water tight.