The MP120K mounting plate is designed to allow the use of 120 VAC to power SpectrAlert Advance horns, strobes, horns/strobes, chimes, and chime/strobes. The MP120K consists of a SpectrAlert Advance mounting plate that has been fitted with a power supply that converts 120VAC to nominal 24V FWR.The MP120K must be installed using a 120 VAC power source. This unit can only be used for non-synchronous applications; it will NOT work with SpecrtAlert SyncCircuit Modules. Also known as -System Sensor By Honeywell-Us 120 ADAPTER PLATE MT F/ HRN STR - BK-MP120K