This 3 piece airlock is designed for homebrewers who ferment their brews in carboys or buckets. It's a simple yet effective device that allows CO2 to escape during fermentation. The airlock fits both glass and plastic carboys, and comes with a #10 rubber stopper. You can use it with any type of yeast, but it's especially useful for high-Krausen yeasts. The 1/2' ID Silicone tubing can be attached to the center post for blowoff use. When fermentation slows down, just remove the tubing and replace the hat and cover. Keep your fermentation process smooth and hassle-free with this great airlock.