A must-have for self defense or roughing it in the back country, the Storm Safety Whistle's patent-pending harmonic chamber makes it the loudest whistle on the planet. When blown, it produces a decibel reading between 118 and 120 dB, more than twice as loud as any other whistle tested, including those used by the police! Safety whistle is easily heard over cheering crowds, waves and wind, and it even works underwater (dive clubs use it to organize multi-diver events and signal a buddy while underwater, and Navy Rescue boats trust its power). An essential tool in your disaster preparedness kit for home, car or toolbox, this whistle's a real blast!