Aiphone AT-406 Box set with AT-206 white audio master station and AT-306 white audio sub master station.

FEATURES Set includes 1 AT-206 master station and 1 AT-306 sub master station Master station calls all connected sub stations Sub stations call the master station only Powered by 6V DC or 4 AA batteries Up to two additional sub stations can be added (AT-306)   SPECSCommunication: Handset (full-duplex)Wire Type: Master Station to Sub Station: 2-cond., overall shield – use Aiphone #822202Distance: 2-Station Set: 2,300'(22AWG), 5,250'(18AWG)                  Master Station to 3rd Sub Station: 1,350'(22AWG), 3,100'(18AWG)