Easiest Mason Jar Fermentation Air Lock: These premium self-opening fermentation lids feature a one-way waterless valve that automatically vents gas when fermenting vegetables at home. This simple one-piece airlock requires no water, burping, or maintenance. Foolproof fermenting accessories: Fermenting vegetables can be challenging without the right supplies and equipment. Internal pressure can build and may cause lids to pop off or jars to break. Exposure to air can spoil the fermentation process, so our one-way valve helps prevent contamination. Right Size & Premium Materials: The fermenter lid, 3.34 inches in diameter, is made of high-quality silicone. Durable and easy to clean, it is dishwasher safe and compatible with wide mouth mason jars. The package includes 5 silicone fermentation lids, with or without 5 metal rings, depending on your selection. Low Profile Design: Our waterless system features a low-profile cover for easier storage. The silicone airlock valve is designed to take up less space, allowing you to conveniently store fermented vegetables in cabinets and drawers. Make probiotic-rich foods at home: Ferment your own sauerkraut and other vegetable ferments. Can be used with cabbage, carrots, cucumbers, tomatoes, garlic, radishes, and more. Support gut health by making natural, probiotic-rich foods at home.