The Genuine Subaru 1.2mm Boost Pill Restrictor (part number 22326KA120) is designed for use in Impreza, Legacy, and Forester models. This performance part acts as a boost controller, allowing for precise control over the amount of boost pressure in the vehicle's induction system. As a classic car part, it is ideal for enthusiasts looking to enhance the performance and tuning of their Subaru vehicle with genuine manufacturer quality.