I believe that that cushion is for the front bulkhead of the carrier. There is a R and a L for each side so the trooper sitting in the carrier bench seat ribs won't hurt (HA HA!} as much when the driver goes from GO to STOP !!! See the TM . I don't see any backrest for the Med version. I can very much stand corrected. Thank you for selling your extra parts to help the rest of us !!!