Safe: Your fermenting lids are made of premium quality food-safe silicone. They are BPA-free & contain no phthalates,tough and durable and easy to clean. 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, burps or maintenance. Foolproof Fermenting Accessories: Fermenting vegetables can be tricky without the right pickling supplies and equipment. Strong pressure is present and may blow off the lid or even burst the glass. Open air can spoil the fermentation, so our one-way valve prevents spoilage. Low Profile Design: Our waterless plumbing system consists of a low profile cover for easier storage. Our silicone airlock valve is designed to take up less space, allowing you to conveniently store fermented vegetables in cupboards and drawers. Make Probiotic-rich Foods at Home: Ferment your own sauerkraut, sauerkraut, sauerkraut, and more. Can ferment any vegetable, from cabbage to carrots, cucumbers, tomatoes, garlic, radishes and more. Get probiotics economically and naturally at home