S-Shape Airlocks with #7 rubber stoppers. (pack of 3 airlocks with 3 matching stoppers)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. Use with a drilled stopper. These stopper fit most gallon jugs and 38mm screw cap jugs., 8 Stopper / Bung with airlock hole, Use with a drilled stopper, These stopper fit most gallon jugs and 38mm screw cap jugs, Country of origin - Canada, Manufacturer name - Home and Kitchen Store.