SuperPro DURO3737K SuperPro DuroBall Rear Upper Control Arm Inner Bushing Set - Evo XSuperPro DURO3737K SuperPro DuroBall Rear Upper Control Arm Inner Bushing Set Evo X Control arm bushings form the vital pivot and link between all core suspension components. SuperPro increases the performance and precision over traditional elastomer bushings with the compound DuroBall bushing assembly. Using an isolated spherical bearing encased in polyurethane provides the precision and articulation of a bearing design with the NVH mitigation of