BMW 4 Series F32, F33, F36, F82, F83 (2013 - 2020) Rear Diff Front Bush Insert - PFR5-1927BLK This is a polyurethane insert that fits into and fills the voids in original bush to stabilise the diff under acceleration. - NOTE: Price is for CAR KIT, NOT per bush… Powerflex price their bushes individually, but we have combined the quantities to make it simple!