Ready to race, or just show off the performance capabilities of the 2018 - 2023 Mustang Add ROUSH Rear Valance Aero Foil Kit, designed to work with the factory quad - tip GT valance Designed utilizing techniques used in racing to improve aerodynamic efficiencies, ROUSH Rear Valance Air Foils work to separate the airflow beneath the car, allowing a smaller portion to follow the under - body contours, adjusting rear downforce. Each piece is made from high - strength TPO (thermal plastic olefin) with a black stipple finish, for an OEM look and lasting durability. The plastic is molded with high - pressure injection, the same process used by OE automotive manufactures, which allows for impact resistance and durable flexibility, while remaining lightweight with low density.