Sound Alert Horn – The Mini horn with maximum sound. Just a touch of your thumb produces a piercing blast that can be heard up to half -mile over land and a mile over water. Palm-size convenience with unlimited uses from casual small craft signaling to personal protection. Ozone-safe. Compact- only 4-1/2 inches tall. Stainless steel, non-corrosive diaphragm. Meets U.S. Coast Guard recommendations for boats up to 39 (12 meters). No need for batteries. 1ounce Perfect for Biking Hikers Walkers PWC Boating and Safety Use.