This set of six universal rubber gaskets is designed to fit the Bormioli Rocco Fido collection of clear glass canning and storage containers size 17.5 oz. and larger. If the original rubber has worn out with use over time, or has absorbed odors from the jar’s contents, simply replace it with a new gasket. Note: 4.25 oz. and 6.75 oz. Fido jars require a smaller gasket.