Works well if you need to work on four computers at the same time with only one mouse, monitor and keyboard. Good device if you have to repair or troubleshoot many computers at one time or to use on gaming computers to switch between computers.
Works well if all computers video outputs that use VGA ports. If you need DVI ports, Trendnet also makes KVMs for DVI as well should you need it.
I bought female DVI to male vga adaptor just in case I run into a situation where Im working on VGA and DVI computers all at once.