This is a heavy, metal case, commercial unit. This is a very popular machine due to its high functionality and durable nature. 2 USB ports, CD-RW bay for image backup, 4 synchronized audio channels, Multi-zone motion record, Free DDNS support, triplex operation, Bi directional audio. PTZ control (most major brands). PDA viewable and will marry to the 4 and 9 channel units via the client software. Recommend Samsung i760 for PDA support.