The Storm® is recommended as the best whistle for mushroom pickers in the journal FUNGI (2009; Voitk et al. Which whistle is the best? FUNGI 2(3); 59-63). It is the loudest whistle on the market. Its unique patented design allows it to be heard up to 2km in a cloudforest and under water, up to 15 meters, because the sounding chamber forces all water to be purged when the whistle is blown. It's perfect for mushroom hunters, divers, lifeguards, and for recreation! Creates a clear, high frequency sound, with a power rating over 75% greater than other referee and safety whistles.