EMS4001 Expansion Master Station

The EMS-4001 adds four powered intercom channels to an MS-2002 or
MS-4002 Master Station, and it provides talk, listen and call buttons
for the added channels. Up to four EMS-4001 Expansion Master Stations
may be connected to the MS-2002 or MS-4002 to can add up to 16
channels (20 channels total). T...