Genuine OEM Audi Engine Coolant Regulator O-Ring, part number 06B121119C. This critical sealing ring is designed to create a tight, leak-proof seal for the engine coolant regulator, preventing coolant loss and maintaining proper engine temperature. It is positioned within the coolant regulator assembly. Measuring approximately 62mm in diameter and 3mm thick, this O-ring is made from high-quality, heat-resistant rubber. Using a genuine OEM O-ring guarantees the correct material composition and precise dimensions for reliable, long-lasting performance in the demanding engine cooling system.