A unique two-piece design allows the fermentation bung to stay in the vessel, releasing pressure when necessary. The bung is made from 100% FDA approved, food grade pure silicone rubber, a durable material resistant to sulfur dioxide.
During fermentation, the bung stays firmly in place, allowing pressure to release while remaining air tight, keeping your beverage safe from oxidation and fruit flies. As your product evaporates over time, the liquid level inside the vessel drops, creating suction to draw the top piece of the fermentation bung down. This vacuum seal eliminates the possibility of further oxidation.