RF Harris Mastr III power supply with battery backup.  This is the supply for the newest more efficient Mastr III.  It works with the 27 Volt DC PA Amplifiers.  This model also has the battery backup feature.  In the event of a power failure it will automatically switch to batteries for seamless communications.  While AC is supplied it will charge the backup batteries intelligently to maintain proper charge.  This unit will NOT WORK with the older 13.6VDC PA Amps.  If you are looking to upgrade to the better 27VDC amp from the older 12VDC amp all you need is the PA and this supply.  I will be listing a lot of RF Harris Mastr II P25 equipment, if you are looking for something let me know I might have it.  The system I am selling was a 5 channel P25 Phase 1 system.