https://www.recodadvr.com/products/4ch-720p-hdd-mobile-dvr-with-4g-gps-wifi-m710-g4f/ 1 Supports 1-4CH 720P real-time recording, AHD 720P and CVBS optional 2 Supports Hard disk for main recording (Max 4TB), supports SD card (max 256GB) for mirror recording; 3 Supports real-time remote viewing through 4G/3G/WIFI(optional), remote video & trace download and playback