Description This item is a fermentation airlock, ideal for the fermentation of wine and beer. It forms a closed system that allows carbon dioxide to be released while preventing oxygen and harmful bacteria from entering, thus allowing fermentation gases to escape and keeping air away from the beverage. Featuring a one-way exhaust water-sealed check design, it effectively prevents back-flush into the fermentation chamber when ambient temperatures fluctuate. Feature - Color: Transparent - Material: PP - Size: 12 x 3.8 x 3.8 cm (L x W x H) - Perfect for home-brewed beer, wine, cider, and pure juice fermentation, as well as secondary fermentation. - Isolates the air from the beverage, expels carbon dioxide and fermentation gases, and prevents flies and harmful bacteria from contaminating the drink. - One-way exhaust water-sealed check valve to prevent back-flush into the fermentation chamber during temperature changes. - Easy to use: Fill the exhaust valve with water, insert it into the brew barrel cover or rubber plug on the fermentation container, and secure with the lid. - Standard size airlock fits any homebrew stopper, cork, cap, plug, bung, or grommet with a 3/8 inch hole. Warm tips: - Please boil and disinfect the airlock with boiled water before use, and clean it with water after each use. - Allow 0-1 cm error due to manual measurement. Packing list: 6 x Fermentation airlock