Check the listing for details. Pro Intercom BP2 Belt Pack Two Circuit, Used. Condition: Used. Listed at 143.75 USD. The A and B circuits operate independently of one another and may be used simultaneously. Only the headset amplifier is shared so both circuits can be monitored on a single-muff headset. The 2 circuits are connected to the rear panel XLRs so a Y-cable or SB1 Splitter Box is necessary for each circuit if you wish to loop through to the next station in that circuit.