Durable pealess Fox 40 whistles will be heard above ambient noise, the roar of engines, breaking waves and thundering gale-force winds. Whistle chambers are designed to self-clear when submerged in water. There are no moving parts to freeze, jam or deteriorate.  Used by referees and coaches at all levels who need every call to be heard. Flawless, consistent and penetrating sound keeps the referee in control of the game.