This is a vintage fuel tank cap for a 1978 Ford Truck F100 F150 F250 F350. It is a new old stock (NOS) item that has never been used. The cap is designed to prevent evaporative emissions from the fuel tank. It is an original equipment (OE/OEM) part with part numbers D8TZ-9030-H and FC-809. The cap is made in the United States and is suitable for use in Ford trucks of the same vintage.