Loop Recording allows you to set video file length to 1/3/5min, it will automatically over writes the earliest file and record over it when storage fills up. With the optional GPS module connected, it can display current speed on screen. You can enter the setup menu and check the GPS signal status. The speed unit KM/H MPH is optional. It can record real-time GPS coordinate in the video file. It can be reviewed with the customized GPS player. High Resolution in Day Night. The mirror dash cam with 4k+1080p front and rear camera, which record with clear video in day and night. 12 inch big screen make it read the license plate of vehicle in front of or behind.