This 4-pack of fermentation lids is made of stainless steel, specifically designed for wide mouth jars, and includes airlock silicone grommets (jars are not included). The lids are engineered to create a secure seal for home fermentation projects, working with standard wide mouth canning or fermenting jars commonly used for sauerkraut, kimchi, pickles, mead, and other fermented foods and beverages. Each lid features an integrated silicone grommet that fits tightly with airlocks, allowing carbon dioxide to escape during fermentation while preventing air and contaminants from entering—critical for safe and successful fermentation. The stainless steel material is durable, rust-resistant, and non-reactive, so it won’t leach chemicals or alter the flavor of fermented items. The 4-pack provides a practical quantity for multiple batches or regular use, and the lids are easy to clean, sterilize, and reuse. They fit most standard wide mouth jars, eliminating the need for specialized fermentation containers.