The Edwards 5530M Adaptatone Millennium is a heavy duty industrial, tone selectable, signaling device capable of producing volume controlled, high decibel tones. It uses a microprocessor circuit to create 27 distinctive tones, selected by setting a dip switch within the unit. The Adaptatone Millennium can be activated from field wired, normally open contacts, or from a 24 VDC external voltage source such as an output of a PLC. PLC compatibility assures no additional loading resistors or relays are required to set up your Adaptatone. Designed for industrial applications requiring high decibel output and microprocessor reliability. Typical applications include emergency warning systems, plant evacuation and security intrusion alarms, process monitoring, shift start and dismissal horns, and paging signals. 1/2 in. (13mm) conduit or surface mounting.