description: It is very suitable for brewing beer, wine, cider, pure juice fermentation and secondary fermentation. Isolate the air in wine/beer, exhaust carbon dioxide and fermentation gas, prevent fruit flies from flying into wine/beer, and prevent harmful bacteria from entering. - A one-way air-sealing check valve. During the change of indoor ambient temperature, prevent from entering the fermentation chamber. Easy to use. Pour water into the exhaust valve, insert the lid of the brewing barrel or the rubber plug on the top of the fermentation vessel, and close the lid. The standard size air lock fits any self-made stopper, cork stopper, lid, stopper, stopper or grommet with 3/8 inch hole. Color: transparent Material: PP Dimensions: length 11.5 cm, outer diameter 10mm, inner diameter 6mm Tips: 1. Before using the air lock, please boil and disinfect the air lock with boiling water. Please wash with water after each use. 2. Due to manual measurement, please allow an error of 0-1 cm.