Their extreme durability extends far beyond just the sort of impact resistance that it takes to survive driving nails. They are also extremely water resistant. In fact, even if water breaches the o-ring seals and completely fills the light, your Elzetta light can continue to function.
The sealed Malkoff LED module is one of the keys to this level of water resistance. Even though water may breach the body of the light, it cannot access the LED or the electronics.
This is a tremendous capability. O-rings crack, tear, and deteriorate over time. Everyone has had the experience of a once water-proof watch or flashlight allow water to enter unexpectedly. It is comforting to know that even if this happens to your Elzetta, you will probably still have a functional light.