The Genuine Porsche A/C Line O-Ring Rear (Cayenne) - 95557374902 is a small rubber ring used in the air conditioning system of a Porsche Cayenne. It is designed to create a tight seal between the A/C line and the rear of the vehicle, preventing any leaks or loss of refrigerant. This O-ring is an authentic Porsche product, ensuring high quality and compatibility with the Cayenne model. It is an essential component for maintaining the proper functioning of the A/C system and ensuring a comfortable driving experience.