Maintain the freshness of your bulk food storage contents with this Planetary Design Airscape bucket lid insert. Ideal for use inside 5 gallon or 11 15/16" diameter straight-walled buckets, this insert is perfect for use in fermenting and pickling or storing dry goods and bulk storage items. This patented, plunger-like Airscape lid creates an airtight seal that keeps out excess air, preventing oxidation and preserving the flavor and freshness of the contents inside the bucket (sold separately). Simply insert it into the bucket by squeezing the handle and pushing it down. As you do this, the oxygen within the bucket is released through a two-way valve in the lid. Once the insert is in place, release the handle. This insert features Fresh-Port technology within the two-way valve that allows the user to introduce gas such as argon or nitrogen (sold separately) into the bucket to further aid in the preservation of its contents. Made with a silicone gasket, this lid fits snugly against the bucket walls. For added convenience, it features a degassing valve that allows it to self-burp, releasing any carbon dioxide buildup on its own. Overall Dimensions: Diameter: 11 15/16"