Genuine OEM Volkswagen Coolant Controller O-Ring Seal, part number 06E121119H. This small but crucial O-ring is designed to create a fluid-tight seal within the coolant system, preventing leaks around components like the coolant controller or thermostat housing. It ensures the integrity of the coolant circuit. Made from durable, heat-resistant rubber, this O-ring weighs approximately 0.001 kg and has a diameter of 0.034 meters. Using a genuine OEM O-ring guarantees the correct material compound and precise dimensions for a reliable seal, preventing coolant loss and maintaining the efficiency of the engine's cooling system.