The ABT204A is a 4-port DVI USB KVM Switch with Audio and Microphone switching function. The ABT204A features the latest True Transparent USB (TTU) Emulation Technology for advanced types of keyboards and mice. It also supports all time DDC emulation for ultimate video compatibility with all graphic display scenarios with the latest operating system such as Windows 7 and Mac OS X. It can help you control, boot and reboot 4 computers using only one set of keyboard, mouse, monitor display and a set of microphone and speakers/headphones.