Review on Get Heard On The Field: Hipat Sports Whistles With Lanyard - Bulk Pack For Coaches, Referees, And Officials by Robert Maysey

I ordered these for a Boy Scout exercise in orienteering and trail/backcountry safety. I learned the hard way not to pass any sort of noise making device while these guys are still indoors. I should have waited till they were heading out into the field portion of the event before giving the participants their emergence whistle. Not only are they extremely and annoyingly loud, but they were also sturdy enough to survive the weekend in the wilds. I would definitely recommend these whistles - especially for the outdoors.