This piece of Motorcycle Luggage may not be as aerodynamic (svelt) as your S.O. in the Pillion Position but it is designed to:
Accommodate and organize a fair amount of extra “gear” without creating top heavy or windage sensitive conditions consistent with a taller/larger bag.
Be deep enough to act as a backrest - (The forward compartment makes a great lumbar support.)
Be narrow enough so that hardbag lids( that hinge forward) clear the “Pillion-Pak” whether attached immediately behind you or behind a passenger backrest on a luggage rack.
Have a dedicated space on the bottom (w/velcro closure) to hold straps, bungees (and rain cover on leather model).
Provide eyelets on top to which additional gear may be fastened.
Pillion - Pak Specs:
The Bag is approximately 14”xl4”x10” tall overall depending upon how full you pack it.