Steeda 2015-2023 Mustang Jounce Bumper/ Bumpstop Kits are height specific for cars running performance lowering springs. They are made from "PUR" polyurethane foam which prevents damage to the shocks and provides a more gentle transition under full spring compression without NVH or harsh contact upon impact between the bumper and the frame. An added benefit is the spring function built into these bumpers that offers comfort as well as added vehicle control when negotiating potholes or other unavoidable obstacles on the highway.