The Fido canning jar replacement gaskets will fit all Fido/Fidelity/Fidenza jars and most wire bail jars with a 3 1/2" to 3 3/4" jar opening To determine the size gasket you need, Don't measure your old stretched out gasket! Close the lid on the jar, measure from outside edge to outside edge If that measurement is about 3 1/2" to 3 3/4" this gasket will fit your jar NEW gaskets are tight. If you are having a hard time putting the gasket on, you can soften the gasket in some warm water, then use your 2 thumbs and work the gasket from one side to the other, the gasket will go on.
