4ch digital video recorder 8ch 16ch, video and audio IO port: RS ... .264 compression camera 16ch 8ch 4ch digital video recorder ModelHDVR3504HDVR3508HDVR3516PriceMOQ:10PCS : HDVR3504: 51$, HDVR3508 58$, ... input/1outputAlarm Mode Motion Detection, Sensor triggered, Video Loss, HDD Full, HDD ErrorAlarm in/out4CH ... setting.USB2.0 Support Mouse, U flash disk backup and upgrade.Network interfaceOne RJ-45 ...