1. Double tube, bigger caliber, louder whistle 2. It can be used in emergencies and dangers in outdoor sports 3. Aluminum alloy material, the surface adopts anodizing technology to make the color, does not fade, and has a longer service life 4. With key ring, it can be hung on backpacks, waistbands and other places to prevent loss and easy to carry 5. Small size and light weight
