Replacement fuel filler neck cap, fits most 1/2/5/10 gallon gas tanks. As shown, the internal thread size is between 1-3/4 and 1.7 inches (approx. 3.9 cm), can only be used with a 1.75 inch (approx. 4.5 cm) tank opening. Please measure the size of your tank opening before purchasing. The improved coarse thread fuel filler neck cap reduces the height of the cap to ensure a complete seal. High-quality materials: These fuel filler neck replacement parts are made of high-quality HDPE material, which allows them to bend freely without breaking during use. The thickened and widened rubber gasket fits better with the bottle cap and prevents fluid from leaking during refueling. Leak protection (Note: As shown, the screw cap of the nozzle cap is hexagonal). The nozzle tube and nozzle cap are threaded, and there is a rubber sealing ring inside the nozzle cap. After use, screw the nozzle cap back on. No oil will leak out, even during transport or if the tank slides down. For covering multiple