They come in various models with channels starting from 4, 8, 16, 24, 32, 64, etc. However the 4, 8 and 16 channel are most commonly deployed as they are more economical. The entry level DVR come with capacity to accommodate 1 HDD however higher models have additional capacity of 2 or more HDD’s. Output can be in various modes likes VGA, HDMI, CVBS and Network. Mobile view over network is provided for easy monitoring whenever required with optional alarms and notifications.