The USB combo receptacle that is used in the TR series is the only one on the market that will fit in the TR. The USB has a ground screw almost dead middle length and bottom orientation on the neutral side.  If the USB is installed in the device with the USB ports to the right side, the grounding screw contacts the “back” of the extrusion causing undue pressure on the snap closure.  In many cases, it was found that the face will not snap in place at all.  If by chance the cover can be force shut there is outward pressure on the face and when someone plugs something in and pulls out, it has been seen that the face detaches from the snap closure.  Therefore; it was decided not to install the USB’s to the right.  This manufacturing practice protects the integrity of the closure.