HyperWhistle is the world’s loudest human-powered whistle, capable of eardrum-shattering volume up to 142 decibels & audible at a distance of 2 miles. For reference, a Boeing 747 hits about 140dB on takeoff. Its compact size makes it ideal for self-defense, survival, & emergencies as well as use by referees, coaches, instructors, & other public address needs. Includes re-usable hearing protectors and an easy-clip neck lanyard.