Barrel style airlock includes an outer barrel, inner plastic dome, and perforated lid. Fill water to fill-line, about 1 1/2 tablespoons, of water. Use filtered or distilled water, not well water or chlorinated water. Insert through the grommet, then attach lid to jar and clamp shut. Top up with water if water level falls below the fill-line, such as when the ferment goes into cold storage.
Appropriate for all jars. Required for room-temperature phase of all jars except 1/2 L jars. May be swapped for a mini airlock to save vertical height when transitioning to cold storage. Hand wash.
Allows a visual passage of gas pressure to escape but allows no air to enter.