Designed utilizing techniques used in racing to improve aerodynamic efficiencies, the ROUSH Chin Spoiler separates airflow above and beneath the Mustang, working to reduce overall aero drag. The included market-exclusive Wheel Shrouds separate the turbulent wheel well airflow from the body's exterior slip stream. This ROUSH exclusive for the 2018-2021 Mustang performs so well in generating downforce, it includes stout supporting brackets to transfer the forces to the chassis. For best results, pair this kit with the Ford Performance Package under-engine tray/belly pan (suggested but not required).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.