When filled with water allows CO2 gas to bubble out and prevents air from getting in. Enclosed design allows for slower evaporation from airlock bubble. Package contains 2 Twin bubble airlocks and 2 universal carboy bungs that will fit 3, 5, 6 and 6.5 gallon glass carboys.

Use this airlock and stopper in your fermenter to create a closed system that allows CO2 out and prevents harmful bacteria from getting in. Fill to the marked line with sanitizer or boiled water.

3-piece plastic airlock with a Snap-On vented cover. This airlock is easily cleaned and easy to use.