Rather disappointing. Not as loud as my Army MP whistle form 1980 (which I still have and use). I wanted this for emergency use, I saw a great video about the invention of the unit and how it came to be, and I thought it's be really loud.  It's more hype that real use and I am disappointed, but for the price it is a hassle to return or complain about, especially since I used it (it touched my lips, ewww). It's not even loud enough to get my dog's attention.