Federal Signal's Audio Master 310-MV is an industrial intercom that provides reliable two-way communications and superior sound quality. This unit has a rugged Type 4X housing and is UL Listed and CSA Certified. The Audio Master 310-MV's standard features include volume control call button balanced line output dust- and water-tight housing listen/talk switch remote device activation and the ability to power another intercom at 24VDC. Remote device activation allows you to activate an auxiliary signal such as a horn or light. The intercom is easy to operate. Press the switch down to talk and release to listen. The 310-MV is ideal for use at oil refineries petrochemical plants offshore platforms pulp and paper mills water treatment facilities airports shipyards or anywhere reliable two-way communication is important for safe and efficient operation.