621501-10 Manual Vent Gas Cap : This marine gas tank cap is engineered specifically for compatibility with classic portable fuel tanks from brands including Moeller and Tempo. Manually Vented Design：Equipped with a twist valve, this vented gas cap for boat fuel tanks enables adjustable ventilation control. It forms a tight, leak-proof seal, and the vent screw can be effortlessly twisted to open or close as needed. Broad Compatibility Range：This marine fuel tank cap works with a wide array of fuel tank models, covering part numbers 031103, 031106, 031109, 031112, 031212, 620003, 620049, 630012, 630013, 630014, 620040, 720040, 730014 and 730025 portable boat gas tanks. Universal Fit for Multiple Brands & Sizes：It is compatible with Attwood fuel tanks in 12-gallon, 6-gallon and 3-gallon capacities, as well as Bass Tracker boat tanks, Scepter 12-gallon and 6-gallon tanks, 3-gallon Quicksilver plastic gas tanks, traditional 6-gallon Dura-Tank Essence plastic tanks, Mercury plastic tanks and Yamaha fuel tanks, among others. Premium Material Construction：Crafted from high-hardness plastic, this boat fuel tank vented cap boasts solid build quality. It is rust-proof, corrosion-resistant and anti-aging, and has undergone rigorous testing to guarantee a long service life. Hassle-Free Operation：No additional tools are required. Simply twist the top of the cap to ensure your fuel tank vents properly and efficiently.