For safety concern, it is necessary to install a rear view camera or parking radar. Our reversing camera support both PAL and NTSC video format, feel free to buy. The parking line is also show up on the screen when reversing the car. The parking radar from us could work with the RoadNavi SatNav system & camera perfectly, it shows distance on screen as well as beeping. Our rearview Mirror can support built-in GPS Navigation System(optional), it support real auto dimming and anti-glare feature.