This item was purchased with the intent to connect three all-in-one printers for maximum incoming fax flexibility. The top was removed and two holes were drilled. Matching holes were drilled into the wallboard, anchors inserted and the top was attached to the wall. The bottom of the unit was reattached with the switch up and the ports down. "A" handles the phone line while "B", "C" and "D" are wired to the printer/fax machines.