SPECS: Sound power: 115 dB Hearing distance: up to 1 mile Dimensions: 2.25" L x .75" W FEATURES: Self-clearing chambers for when whistle is submerged in water Solid design to avoid deterioration or jamming of moving parts Volume responsive to breath strength Simple to use without over-blowing ADDITIONAL DETAILS: Includes split ring Favored by referees, coaches, and rescue professionals across the world