An air-lock is a small device, that when filled partially with water, acts as a water trap. Once you have the correct size rubber stopper, you can attach the air-lock by placing its stem into the hole of the rubber stopper and then putting the rubber stopper into the hole or opening of the container.

A fermentation lock or airlock is a device used in beer brewing and winemaking that allows carbon dioxide released during fermentation to escape the fermenter, while not allowing air to enter the fermenter, thus avoiding oxidation. For additional information regarding the product, please contact with DuBuy support team.