Givi produce a Mono Plate to fit the standarrd Yamaha O/E plastic rack. This allows owners to keep the neat Yamaha rack and allow the fitment of a Givi Top case, instead of the very expensive Yamaha topbox. 
It is available to fit the 2006 - 2020 model FJR's. Fitment of this plate allows use of the standard Yamaha panniers at the same time.
Mounting plate to Yamaha rack materials is Metal
Givi plate to Topcase material is Nylon
GIVI ALI  Rear Plate is a bike specific aluminium rear plate kit for Yamaha FJR 1300 2006-2020 models, The plate gives a smart adventure look to the FJR and is designed to take GIVI Monokey Top Boxes. All parts needed to mount the GIVI  Aluminium Rear Plate are included.