Package contains: 3 x airlock, 3 x locks and 3 x airlock covers. Airlock height: 17cm, width: 5cm. Material: made of high quality PP plastic, environmentally friendly, non-toxic, harmless, bacteria-free, safe to use. Easy to use: l The operation is simple and convenient, just put water into the exhaust valve, put it into the lid of the brewing vessel or the rubber stopper on the top of the fermentation tank, and close the lid .Without manual control, simple, operation, and can also long-term repeated use. Easy to watch: you can check the fermentation, the transparent airlock allows you to look inside so that you can watch the airlock do the hard work for you. Usage: This valve allows fermentation gas to escape and prevents harmful bacteria from entering. Can be used for home brew beer, wine, cider and other uses.