It can release carbon dioxide and be used in the fermentation of wine and dairy alcohol, and can prevent oxidation. [Good airtightness] The good airtightness of the fermentation airlock facilitates fermentation, effectively isolates the air, and prevents oxidation. Automatic exhaust at room temperature without manual control. [Easy to put on and remove] This type of dust cap has a textured surface and will not slip when opened. There are 3 buckles inside; press it gently downwards to secure, and pull it up and twist to open. The lid does not need to be drilled as there is a crevice that allows gas to escape. [Reusable and Versatile] These airlocks are solid and reusable. They can last for a long time. Simply place in your disinfectant and use again and again. The airlock can be used for fermentation projects to preserve food, beer, wine, sauerkraut, cider, fruit wine, rice wine, broccoli, carrots, ginger, and brew. Suitable for kombucha, wine, and other fermentation applications. Suitable for pure fermentation, such as white grape, mead fermentation, red wine secondary fermentation, etc. Color: Transparent, Red, Black Material: PP Size: 17cm Package Contents: 6 x Airlocks 12 x Sealing Rings Only the above package content; other items are not included. Note: Light reflection and different displays may cause the color of the item to appear slightly different from the real thing. Measurement allowance is +/- 1-3cm.