... DVR functionFeatures:Built-in 3.5" TFT monitor, rearview with camera,auto start working while car backward Built- ... FM frequency transmitter connect to your car stereo,total 7 points available Universal audio input for audio devices, ... button 3 seconds to open the DVR video on mirror,press"PLAY"button 3 seconds again to close ... be set and shown on display Hot sale Rearview mirror with 3.5" TFT with DVR