The D8125 Addressable Expansion Module works with the D9127U or D9127T POPIT Modules to provide multiplex technology that combines zone or point supervision with individual device addressing on one pair of wires. Use the D8125 to provide expansion beyond the standard number of control panel zones, up to a total of 238 points. Each D8125 module can fully supervise 119 D9127U or D9127T POPIT Modules.