Acme 660 Thunderer Plastic Whistle is made from high-impact plastic that is designed to withstand years of use. It provides high volume and far reaching penetration with ease of blowing. It is used by referees in a variety of sports, including hockey, soccer and basketball. Possibly the biggest selling whistle of all time, easy to blow, small, high pitch 117dBA and loud. 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.