INCLUDED IN PACKAGE --- You will get 4 plastic airlocks and 20 black silicone grommets, enough for you to use and replace. Makes fermentation easier --- This set of airlock is an excellent fermentation tool for kimchi, sauerkraut brewing or fermentation, it can provide reliable sealing, effectively isolate air, prevent oxidation, and help fermentation throughout the fermentation process. /p> S-type design: The S-type airlock has 2 vertical chambers connected by a kind of drain siphon which greatly helps to keep oxygen out of your beer, allowing your beer to produce water. alcohol instead of vinegar. SAFE MATERIAL --- Made of food grade PP plastic, these plastic storage airlocks are odorless and non-toxic. At the same time, the airlock grommet is made of silicone, which is durable and soft, and can be used for a long time. Wide range of applications - Airlock kit can be used as fermentation equipment multifunctional for various purposes, such as food preservation, fermentation of cabbage, pickles, sauerkraut, grape juice, etc., or fermentation, beer, wine fermentation.