The Acme Tornado Whistle 636 is a powerful pealess whistle with a slim and compact design that has earned it the title of "the little whistle with big punch." The Tornado 636 works when wet as well as in sub-zero temperatures, and it takes minimal effort to blow. The patented top venting system prevents accidental sound blocking/muffling by your hand during use. It's S.O.L.A.S (Safety of Life at Sea International Regulation) approved and used by the Mountain Rescue Council. This whistle has a higher pitched tone than the Acme Survival Whistle. We've priced these whistles at a substantial discount in bulk to make it possible for clubs to give ring crew their own whistles for hygiene's sake. Size is 1.75" x 0.75" x 0.25". Available in assorted colors; please allow us to choose for you.