Fox 40 whistles feature a patented pealess design using harmonically tuned sound chambers to develop the trill. This whistle will never fail, it won't freeze, it can't jam, and it works wet. The Fox 40 is the official whistle of the NFL, the NBA, the NHL, as well as the US and Canadian Coast Guards. It's high pitch is designed to be heard over crowd noise so it works exceptionally well at overcoming the noises of wind, rain, and waves. It works GREAT for training dogs! Comes complete with a lanyard!