The M1000-USA masking speaker system was created to precisely recreate the necessary spectrum of masking transmission into the plenum area. The revolutionary 734 cubic inch square enclosure assures ample low frequency response. A exclusively designed 8" dual cone loudspeaker is included in the package. A high efficiency 70.7V internal transformer is coupled to an external tap selector switch for simple system tuning. For more precise adjustments, an off switch and a wide selection of wattage taps ranging from .25 watts to 4 watts are provided.