ERI Whistle...a voice saver that penetrates the wilderness. Conserve your energy and voice by whistling searches to your location. Loud, 3 chambered, non-lip sticking plastic surface carries farther and longer than your voice. Also contains a built-in button compass and a fastening clip. Inexpensive insurance for you and your loved ones. When you are finished shopping, please visit www.eri-online.com.