Captain ORing – Boat Deck Fill Cap ORing Seal Gaskets for " .
WEBRestore the air tight and water tight seal on your deck fill caps with Captain ORing's replacement marine deck fill cap orings. Designed to fit deck fill caps with a 11/2" thread OD (outside diameter at the cap threads). These orings feature an inside diameter of approximately 11/2", a thickness of just over 1/8", and an outside diameter just over 13/4".