Kilner 1L Fermentation Jar Set of 2The Kilner 1L Fermentation Jar Set of 2 provides the easy way to create smaller batches of your own delicious fermented foods packed with vitamins, minerals and probiotic cultures. The silicone valve in the lid will release the gas that builds up inside the jar during the fermentation process, whilst also blocking the air from entering the jar, which usually causes foods to go mouldy. Perfect for creating live cultures of sauerkraut, kimchi, pickles