BMW 4 Series F32, F33, F36, F82, F83 (2013 - 2020) Front Radius Arm To Chassis Bush - PFF5-4001 This is a replacement part that uses our Black Series material to boost stiffness over the original part by 18% to withstand increased loading seen by this position on the car. For a caster adjustable version please use PFF5-4001G. - NOTE: Price is for CAR KIT, NOT per bush… Powerflex price their bushes individually, but we have combined the quantities to make it simple!