Deck Fill Replacement Cap & ChainThis Attwood Replacement Cap and Chain is made for Attwood deck fills. The flush cap is slotted for a separate key and features an O-ring that seals the cap watertight. Features:Cap is attached by a stainless steel beaded chainSpecifications (Cap and Chain are Fitted for This Deck Fill Size):3-1/4 (inch) Fill Neck Length1-7/8 (inch) installation hole size3-inch flange sizeFits 1-1/2 (inch) I.D. Hose*Key sold separately Deck Fill Replacement Cap: The "Deck Fill Replacement Cap" is the top cover of a deck fill fitting on a boat. A deck fill fitting is a component installed on a boat's deck that provides access for refueling. The cap covers the fill port to prevent debris and water from entering the fuel system when not in use. This replacement cap is likely designed to replace a worn or damaged cap on an existing deck fill fitting. Chain: The "Chain" is typically attached to the cap and the deck fill fitting to prevent the cap from being lost or dropped overboard when it's removed from the fitting. The chain keeps the cap connected to the fitting, ensuring that it remains secure and easily accessible.