Identify the label on the rack supports (F) to find the location identifier ('FL' = Front Left, 'FR' = Front Right, 'ML' = Middle Left, 'MR' = Middle Right, 'RR' = Rear Right, 'RL' = Rear Left). The rack supports must be installed at the correct location on the vehicle as indicated by the label. The Defender 90 will not require the x2 middle supports.