Here is a combination whistle/buckle - If you are concerned about weight,the unit weighs all of 0.35 oz. i purchased one and put it on my day pack - why not? http://www.rei.com/product/848923/gear-aid-whistle-sternum-strap-buckle-kit-34

Not actually all that loud, but it certainly is handy


Edited by hikermor (03/30/15 03:34 AM)
_________________________
Geezer in Chief