Acme 660 Thunderer Whistle 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 660 Thunderer is favoured by customers in colder settings where metal might stick to the skin. Also chose by officials in sports, teaching, animal training, police authorities, military units and music specialists. Available in Black, Blue, Day Glow Orange, Green, Luminous, Orange, Red White and Yellow.