This product is a genuine engine coolant reservoir designed specifically for Volkswagen and Audi vehicles. The part number is 5WA121407F. It is used to store and supply coolant to the engine to regulate its temperature and prevent overheating. This reservoir is an authentic OEM (Original Equipment Manufacturer) part and is made to the highest quality standards for optimal performance and durability. It is a direct replacement for the original reservoir and is compatible with various models of VW and Audi vehicles.