RioRand 3.0 Inch Hd Lens 170 Wide Angle 1080p Car DVR GT500 Vehicle Camera Video Recorder with Gravity Sensor and Rearview Video Function (Blue) Powered by RioRand Advanced Technology G-Sensor: DVR will save videos as undeletable files when gravity acceleration, any accident happens. SOS function :Under recording mode, press UP button momentarily to activate SOS function, the current video will be saved as undeletable file. Parking movie: When the car stops and the G-sensor inducts collision,the dvr will automatically power on and record 8 seconds,the video will be saved as undeletable file.