The Acme No. 660 Thunderer Whistle is possibly the biggest selling whistle of all time. Easy to blow, small, high pitch and loud (117dBA), the Thunderer is favoured by customers in colder settings where metal might stick to the skin. Also chosen by officials in sports, teaching, animal training, police authorities, military units, and music specialists. Ideal for sports, gym classes, in teaching, as a coaching whistle, for dog training, as a safety whistle, for walkers and ramblers, and more!