Fox 40's patented, pea-less whistle technology exceeds all sound and design barriers, with an ear-piercing tone that is distinct, powerful and omni-directional. Waterproof and unbreakable, Fox 40 delivers optimum performance and sound power in a surprisingly small, compact and functional package. They can be heard over a mile away; this faultless performance and reliability has made Fox 40 whistles the preferred choice for personal safety and rescue professionals worldwide.