HDView 4 CH Channel 720P HD-SDI Commercial Grade Security DVR Surge Protection, 1080P HDMI, Digital Video, Only Work with 720P/1.3MP SDI Cameras 4 Channel 720P HD-SDI DVR Only Work with 720P/1.3MP SDI Cameras 720P Super Clear Megapixel Video Digital Video, NOT Analog Advanced Mobile Phone App, No Hard Drive Installed