Genuine OEM Volkswagen Hexagon Bolt, part number N91140901. This bolt is engineered for secure fastening within the engine cooling system, ensuring components remain tightly mounted under operating conditions. It is manufactured to exact specifications to provide the necessary clamping force and vibration resistance. Using genuine OEM hardware is critical for maintaining the integrity of cooling system seals and preventing leaks, as these bolts are designed to withstand specific thermal expansion cycles.