The After Shake 3-Frequency Emergency Whistle is made of high quality ABS plastic. Metal will stick to your mouth in cold weather making it difficult to use.
This whistle uses three separate chambers to produce a combined multi-pitch sound alert with minimal effort from the user. Variations in the frequency of sound are what makes your signal stand out in areas of varying ambient noise such as wind, rivers and city streets. The high pitch allows search & rescue dogs to hear you immediately.