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 may cause standard lids to pop off or potentially damage the jar. 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 compact silicone airlock design saves space, allowing you to store fermented vegetables conveniently in cabinets or drawers. Make Probiotic-Rich Foods at Home: Easily ferment sauerkraut and a variety of vegetables such as cabbage, carrots, cucumbers, tomatoes, garlic, radishes, and more. Support digestive health by making natural, probiotic-rich foods in your own kitchen.