Newly patented two-chamber pealess whistle.
Sonic Science perfects the whistle. Our newly patented two-chamber design eliminates the pea (cork ball) normally needed to produce a "trill". Instead, two harmonically tuned air chambers create a wave energy phenomenon called a "beat". As a result, the Fox 40 produces an extremely loud, high penetrating "trill". And because there's no pea to stick and impede sound, you can't overblow a Fox 40 and it won't freeze up in the colder months.
Available in 2 colors and 2 sizes.