The Carboy Dual Ferm Bung is designed to fit over the top of your carboy so you never have to worry about an airlock/stopper popping off of your carboy. The unique feature of this bung is in its two-piece design. It mimics the Barrel Dual Ferm Bung in design, when set to the open position, the bung acts as an airlock and allows the release of CO2 while maintaining a seal against oxygen coming in. This makes the bung ideal for alcoholic or malolactic fermentation. When fermentation is over and you no longer want the bung to release CO2, simply push the center cap into the bung to create a firm seal and the bung becomes a solid stopper!
These bungs are made out of 100% Food Grade Silicone! And made right here in the USA, and in fact in California. Don’t be fooled by imitators selling cheaper bungs. These bungs tend to be from CHINA and are not composed entirely of food grade silicone. For your wine’s sake, we think you should go with a sure thing, especially a sure thing that is in constant contact with your wine.