the display relates to a visual display box that is supposed to be installed but has walked away, the audio is good enough tho, makes reverse parking much easier!!!
i would recomend them to any driver/car especially ones where you can see naff all at the rear!!!!
Personally, I think an 18"x12" RSJ at the back is the best reversing sensor-just keep going back until you feel the bump or hear the sound of broken glass.