S-shaped airlocks are the "OG" airlocks for home beer and winemaking. They have a smaller chamber so you can more closely observe the CO2 rising and therefore the rate of fermentation. They cannot be cleaned manually if they get dirty during the ferment. The 3-piece airlock that allow CO2 to escape easily. This airlock is open at the bottom, allowing Krausen foam to enter the airlock if necessary.