Originally Posted By: JerryFountain
Phaedrus,

Nearly all glass breaking tools are usless underwater. There is no friction with the ground to swing one quickly and water resistance slows it down. Automatic center punches would work but unless there is something to hang onto you cannot push it in to cock the spring.


It uses a spring loaded punch. Since my truck isn't an extended cab it would be hard to imagine the circumstance where I couldn't find anything to braced myself on.
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“I'd rather have questions that cannot be answered than answers that can't be questioned.” —Richard Feynman