We recently discovered this premium breathable silicone barrel bung and were immediately impressed with its robust design and features. To start with, the ridge really helps make bung removal effortless. 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 in barrels or tanks. 

• Fits 30- and 60-gallon barrels as well as the hole in the lid of most Variable Volume tanks!
• Also fits perfectly in a 2" tri-clamp ferrule
• Replaces Stopper Sizes #10 , #11, #12
• Stopper Measurements: 1.65" x 2.19" (42 mm x 55.5 mm)
• The flapper stopper protrudes roughly 2.5" from the stopper to allow for easy assembly