The Gembird KVM switch only features transmission of video and input device signals (PS/2). USB or sound signals are not supported by this box. Client computers are selected using one of four keys located on the front side of the KVM unit. An LED on the console indicates which computer is currently being supported. An additional LED shows which of the four client ports is connected with an active computer. If only VGA signals are being fed to the box, then these LEDs do not light up.
Each client computer has its own switch knob on the KVM switch.
The labeling on the various KVM box connections is exemplary.