This product is made of high-quality ABS, with light weight and small volume. It can be hung on the key chain. Color and appearance are what most people like. Suitable for ball games, referees and outdoor exploration. Suitable for running, fitness equipment, outdoor sports, swimming and wading. It is suitable for coaches or PE teachers. It is suitable for use in sports grounds or swimming pools. The whistle weighs 7.3 grams and is 5.3 cm * 2.3 cm * 2.1 cm long. It is very convenient to carry.