The 'Air Filter Housing Top Nut' for the Citroen 11CV Perfo is a vital fastening component that securely holds the air filter in place. Specifically designed for the classic Citroën 11CV, this nut ensures precise fitting and sealing, maintaining optimal engine pressure and airflow. This increases the efficiency and longevity of the engine. Made from high-quality material, it provides a reliable and durable solution for your vehicle. Replacing worn or damaged fasteners can improve performance and reduce unusual engine noises. Ideal for enthusiasts looking to keep their vintage car in top condition.