It can emit carbon dioxide for honey,white wine,milk wine alcohol fermentation and can prevent oxidation. Easy operation,simply fill water into the exhaust valve,insert it to the cover of the brew barrel or rubber plug on the top of the fermentation container and then cover it with the lid. Effectively prevents flies flying into the wine/beer with a cover included. All of the fermentation process is automatic fermentation without manual control and can be repeatedly used for a long time. Suitable for pure juice fermentation,such as white grapes,honey wine fermentation,red wine secondary fermentation,etc. Condition:100% Brand New Sub-Type:Airlocks Product Length:Approx.17cm/6.7inch Product Max Width:Approx.1cm/0.4inch Product Weight:Approx.18g Type:Bar Accessories Bar Accessories Type:Wine Check Valves Feature:Stocked Feature:Disposable Feature:Eco-Friendly Quantity:1 Model Number:Wine Check Valves function:Brew One Way Valve,Brew Check Valve, Color:transparent material:plastic Package Contents: 5* Brew Check ValveOnly the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.