Grandstream GVC3550 Network Video Recorder (NVR), 1 x Gigabit Ethernet, H.264, 1 x HDMI, 1 x VGA, supports up to 4 x 3.5 inch SATA hard drives (maximum 16TB storage), 1 x eSATA, 2 x USB 2.0, supports Grandstream IP cameras and third party ONVIF compliant SIP cam (GVR3550_XX) 

http://www.grandstream.com/sites/default/files/Resources/gvr3550_english_datasheet.pdf