Genuine OEM Volkswagen O-Ring, part number WHT009138. This O-ring serves as a circular seal to prevent leakage within various systems, specifically noted for use in coolant hoses. It is positioned at connection points to ensure a tight seal. The O-ring has a diameter of approximately 39mm and a thickness of 4mm. Genuine OEM O-rings are manufactured to exact tolerances, ensuring reliable sealing and preventing fluid loss, which is critical for the longevity of cooling system components.