Coghlan’s Four Function Whistle is a useful multi-function device is excellent for reading a map and orienteering. The whistle features 4 key functions that are helpful in navigating the outdoors. Includes a compass for finding your direction and when orienteering. The built-in whistle is loud enough to alert others of your presence. On the back of the whistle is a thermometer that accurately tells the temperature and inside is a magnifier that is useful for reading maps or viewing details on items. The Four Function Whistle also includes a convenient clip to attach to a zipper, belt, lanyard, or backpack.