West Marines Storm Safety Whistle sounds a powerful blast you can hear underwater! Even if it's drenched, our Storm Safety Whistle emits a piercing blow. Special self-draining chambers quickly purge water so it can sound a blast many times louder than U.S. Military whistles. Constructed from sturdy plastic with easy-to-grip ridges, this whistle is ideal for safety on your boat and attached to a life jacket in case of an overboard emergency. Key Features: Works even when wet Easy to grip ridges for ease-of-use Loud blasts for effective emergency signaling