This 8 port transmitter unit is designed for use with startechcoms st121 vga video over cat 5 extension series this convenient video distribution system simplifies implementing digital signage solutions by allowing a single vga source to be broadcast to multiple displays at up to 492 ft 150m away comprised of an 8 port vga extender unit this device st1218t or a 4 port vga extender unit st1214t and one st121r receiver unit per display as necessary the vga and audio extension series