Genuine OEM Volkswagen Coolant Regulator, part number 03H121113C. This part controls the flow of engine coolant to the radiator, helping to maintain the optimal operating temperature. It features precise internal mechanisms to ensure accurate temperature regulation. Constructed from durable materials to withstand engine heat and coolant exposure. Genuine OEM regulators are calibrated to factory specifications, ensuring precise temperature control, preventing overheating or undercooling, and contributing to overall engine efficiency and longevity.