Used by Special Forces worldwide, this whistle is a must in all kinds of rescue situations. One of the loudest of its kind at 122dB, it can be heard above most natural and manmade noise, and won’t freeze, clog, or rust like traditional whistles. Compact and lightweight, just over 2" in length and less than 1/2" thick, it can be used by adults and children in the water, on the trail, or even in the city. 100% waterproof.