Using an airlock when you are fermenting vegetables in Mason jars will keep out oxygen while still letting the CO2 produced escape. An airlock greatly reduces the chances of a moldy ferment. If you use an airlock plus one of our glass fermentation weights to keep your ferment under the brine there is little chance of mold. Fill the airlock halfway with clean water, vodka, or sanitizer solution and stick it into your fermenting lid. Our silicone fermenting lids will accept this airlock as is, but other lids might need some kind of drilled rubber stopper or grommet. Because vegetable ferments can easily overflow the airlock, 3 piece airlocks are better than S shaped airlocks. You won't need a pipe cleaner if brine gets into the airlock. The plastic is dishwasher safe.