|This cap has secure sealing and easy finger tip operation. These caps are made from the highest quality modern engineering plastics with Viton o ring seals (which can be easily replaced if you should ever need to do so.) The mounting ring is anodized aluminum with the flange recessed to give a perfect flush fit whether it is riveted under a metal skin, as in the RV series, or built into a composite structure. This cap is non vented and recommended to keep the fuel in, the water out and in the locking version, other unwanted items out of your tank. Size: 65 mm O.D.; Wt: 80 grams. SPRL caps are used on Europa, Compair, Glasair, Lancair, Murphy, OMF, Rocket, Velocity, Zenith and many more experimental aircraft. Manufactured by SPRL.|
The diameter of this cap is 65 mm or approx. 2.56 inches.
Per the supplier: It is made out of Aluminum. It can be welded but it is anodized and will have to be properly stripped. We recommend "the flange can be riveted to an alloy skin, drill proper edge clearance in the thin skin and accept marginal clearance in the relatively thick flange."
The replacement o-ring for this will be Part # 05-02611.
If you are referring to the o-ring it measures to 2.45" but if you are referring to the outer flange that measures to 3.45".