【Loop Recording & G-Sensor & Supports 128G SD Card Max】When the SD card is full, it will cover the previous video file to continue the recording.This device has built in G-Sensor, if collision occurred to the car,the backup cam mirror will automatically locked the special video file, which will not be covered by the loop recording and stored to ensure that the most important videos are not lost. In addition, the dash cam supports 128G SD card max (not included),can record more important moments.