Genuine OEM Volkswagen Coolant Body with Thermostat, part number 07D121111AR. This part houses the engine's thermostat and controls the flow of coolant to maintain optimal operating temperature. It is a critical component of the engine cooling system. The unit measures approximately 0.26m in length, 0.125m in width, and 0.095m in height. Genuine OEM coolant bodies and thermostats are manufactured to precise tolerances, ensuring accurate temperature regulation and preventing engine overheating or undercooling, which is vital for engine longevity and performance.