outdoor survival whistle - high-frequency aviation aluminum whistle - double hole high decibel referee whistle

material: aluminum alloy specifications: 56 * 15 * 8mm weight: 12g features: 1. compact and easy to carry, no ball design, internal water can also be used; 2.aluminum alloy, double hole design, high decibel, spread far. it is a good tool for outdoor survival, fire and earthquake distress distress and training. 3.distress in the wild, the field rescue survival whistle played a considerable role. and we can make a whistle language and send messages to teammates.