Genuine OEM Audi Refrigerant Circuit Expansion Valve, part number 4M0820181B. This critical component controls the flow of refrigerant within the air conditioning system, ensuring efficient cooling and proper pressure regulation. It is specifically designed for the rear AC circuit. Constructed from robust aluminum, this valve measures approximately 8.2 cm in length and weighs 0.181 kg. Opting for a genuine OEM expansion valve guarantees precise factory calibration and material integrity, essential for the optimal function and longevity of the vehicle's climate control system.