Genuine OEM Volkswagen Coolant Regulator Housing with Thermostat, part number 03P121111E. This housing contains the thermostat, which is crucial for regulating the flow of coolant throughout the engine cooling system, maintaining optimal operating temperatures. It is typically located within the engine bay, connecting various coolant hoses. Constructed from durable, heat-resistant plastic, this component weighs approximately 0.333 kg. Using a genuine OEM housing ensures precise fitment, reliable temperature regulation, and proper integration with the vehicle's cooling system, preventing leaks and overheating.