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: 70 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.