Markwort Windstorm Whistle- International Retail Blister Card World's Loudest Referee Whistle Campers, Hikers, Hunters Screams about virtually any noise The Windstorm Safety Whistle is ideal for all your favorite outdoor sports like hunting, diving, and hiking. The smaller size of the Windstorm makes it perfect for high school, collecge and pro sports referees, coaches and game officials. Used by Police Departments, the U.S, Military, U.S. Coast Guard, and Emergency & Diving Operations who appreciate their all-weather use; each whistle purges moisture yet still delivers a loud, penetrating sound easily heard in any environment. Blown and heard on land, up to 1/2 mile, and even underwater, up to 50 ft. A non-corroding thermoplastic housing is easy to grasp, and the patented double chamber design allows it to be blown when held reight side up or upside down.