Outdoor explosive whistle Double tube high-frequency whistle Aluminum alloy metal survival whistle Product name: High decibel double cavity aluminum alloy whistle for survival Material: aluminum alloy Specification: 56 * 15 * 8mm Weight: 12g Features: small, convenient and easy to carry, no ball design in the inner cavity, and it can also be used in case of water inflow; It is made of aluminum alloy and designed with double chambers. It is high in decibels and spreads far. It is a good tool for outdoor survival, fire and earthquake rescue and training. The whistle plays a significant role in the field rescue and survival. Although we have better electronic communication equipment, the role of the whistle can not be ignored. Once modern communication equipment has no power supply, signal shielding area, military restricted area, location determination, water danger, etc., the whistle will show its strength. And we can make our own whistle language to pass information to our teammates