Dahua 16 Channel Compact 1U 1HDD IP Network Video Recorder (DHI-NVR4116HS-4KS2/L) - Main Processor: Industrial-grade embedded processor, Resolution: 8MP; 6MP; 5MP; 4MP; 3MP; 1080p; 720p; D1, Access Channel: 16, Storage: Local HDD; network, External Port: Audio Input: 1 × RCA input, Audio Output: 1 × RCA output, HDD: 1 SATA III ports, up to 10 TB for a single HDD. The maximum HDD capacity varies with environment temperature, USB: 2 (1 × front USB2.0; 1 × back USB2.0), HDMI: 1 (supports up to 4K resolution output), VGA: x 1, Network: 1 × RJ-45, 10/100 Mbps self-adaptive Ethernet port, OS: Embedded Linux