SWIMRUNNERS emergency whistles are lightweight and emits a shrieking, high-pitched sound. The whistles can be used with a lanyard or clipped directly onto your belt or wetsuit zipper. The finger grip area makes the whistle easier to hold with cold hands. The whistle is waterproof and durable. The design won’t rust, clog, or freeze and works in all weather conditions. SWIMRUNNERS whistles in polypropylene construction is a non-corroding whistle which will float in sea water.