No External Power required. Output Port Selectable. Tran sparent to the user. OS Compatibility: WIN98, WIN ME, WIN 2K and WIN XP. AS251S allows 2 PCs to share 1 serial (RS232) printer. It is easy to install and needs no additional power supply. Network Connectivity technology Wired Technical details Depth 93 mm Compatible operating systems WIN98, WIN ME, WIN 2K, WIN XP Manual Yes Height 25.5 mm Width 77 mm Material Plastic Ports & interfaces I/O ports 1/2 RS232 Operational conditions Operating temperature (T-T) 0 - 50 °C Operating relative humidity (H-H) 0 - 80% Weight & dimensions Weight 50 g manual pdf