Commonly seen on A-2 jackets. Would make an awesome accessory to your A-2 jacket. http://www.ebay.com/itm/Vintage-THE...ltDomain_0&hash=item416a1d2daa#ht_1781wt_1124
During my career as a lifeguard, I had several Acme Thunderers. It was the best and most popular whistle on the market, and was used by referees as well as lifeguards. I still have one around here somewhere. May be buried under all the pea coats when the rack and shelves took a dive the other day. Today the refs, and probably the lifeguards as well, use the Fox 40, a black plastic whistle. I also have a few of those. The Acme Thunderer in nickel is still available, and, in my opinion, still the best.
My mother used a couple as a school teacher, I still have them. Yes they are very loud! I also have a Bobby whistle that came with my WWII A2, from a friend of the family.