The BAL-8 is a 1RU interface containing eight 4-pair, transformer-isolated ports. Each port handles two audio signals and two RS-422 data lines. The unit isolates the connection between Matrix Plus 3 ports and peripheral devices such as two-way radios. Each set of input/output connectors has its own slide switch, allowing the port to be placed into Normal or Interface mode. In normal mode, the data pairs are unaffected, while in interface mode they are connected to indicate to the system software that a direct connection is being made. Each channel has a pair of RJ-45 connectors for input and output.