Genuine OEM Volkswagen Expansion Coolant Tank, part number 1K0121407A. This component is essential for the cooling system, holding excess coolant and accommodating volume changes as the engine heats up and cools down. Made from durable plastic, it weighs 0.302 kg and measures 0.2m in length. Choosing a genuine OEM expansion tank ensures proper fluid level management, prevents system over-pressurization, and maintains overall cooling system reliability.