Genuine OEM Volkswagen Coolant Hose, part number 5QM121109. This hose transports coolant between engine components and the cooling system, vital for maintaining optimal engine operating temperatures. It is located at position 10 in the diagram. Genuine OEM coolant hoses are designed to withstand high temperatures and pressures, ensuring reliable coolant flow and preventing leaks, which is essential for the longevity of the engine.