3-Piece Plastic Fermentation Airlock Water airlock for fermentation of beer, wine, moonshine, pickles, sauerkraut. Brand new in sealed package.Doesn't allow reverse air transfer.Simple, effective air lock.Creates a closed system that allows CO2 out and prevents oxygen and harmful bacteria from getting in.Standard size airlocks made to fit any home brew stopper, cork, cap, plug, bung, or grommet with a 3/8" hole. Fill to line with water or sanitizer.Use with a drilled stopper. Easier to clean than the double bubble.Guaranteed exceptional quality. Professionally shipped within one day. Buyer receives one 3-piece Airlock new in sealed plastic, as shown in photo.