It releases carbon dioxide and can be used in the fermentation of white wine and dairy alcohol, helping to prevent oxidation. [Good Airtightness] The fermentation airlock provides excellent airtightness, facilitating efficient fermentation by effectively isolating external air and preventing oxidation. It allows automatic exhaust at room temperature without manual control. [Easy to Put On and Remove] This dust cap features a textured surface for a non-slip grip when opening. It has three internal buckles—gently press down to secure it with a click, then pull up and twist to open. The lid does not require drilling, as a built-in crevice allows gas to escape. [Reusable and Versatile] These airlocks are durable and reusable, designed for long-term use. Simply sanitize in your preferred disinfectant and reuse multiple times. Suitable for various fermentation applications including food preservation, beer, wine, sauerkraut, cider, fruit wine, rice wine, broccoli, carrots, ginger, brew, kombucha, and more. Ideal for pure fermentation processes such as white grape fermentation, mead fermentation, and red wine secondary fermentation. Color: Transparent, Red, Black Material: PP Size: 17cm Package Contents: 6 x Airlocks 12 x Sealing Rings Note: Light reflection and differences in display screens may cause slight variations in color appearance. Measurement error allowance is +/- 1-3cm.