The 2 fermentation jars 34 us fl oz provides the easy way to create smaller batches of your own delicious fermented foods packed with vitamins, minerals and probiotic cultures. The introduction of a silicone valve in a 34 us fl oz preserve jar lid will release the gas that builds up inside the jar during the fermentation process. However, the atmospheric air will not enter the jar usually causing food to go moldy. Perfect for creating live cultures of sauerkraut, kimchi, pickles and much more. Creating your own fermented foods is straight forward, just add your favorite vegetables, water, and salt.