Our 5530M, 5531M and 5536M Adaptatone Millennium devices are heavy-duty industrial, tone-selectable, stand-alone signals capable of producing volume-controlled, high-decibel tones. They use a microprocessor circuit to create 27 distinctive tones, selected by setting a miniature dip switch within the unit. The Adaptatone Millennium can be activated from field-wired, normally open contacts, or from a 24Vdc external voltage source such as the output of a PLC. The 5536M can also accept signals from a Central Tone Generator.