The Aiphone MC-A/A is zone paging adaptor used in the Market Com system, a maximum of 60 station paging and intercom communication system. Features: Controls up to maximum of 60 MC-60/4 phone stations. Has inputs for background music Treble, bass, and volume controlsfor paging and background music Pre-page chime tone, adjustable Connects to any standard paging amplifier Specifications: Power source: DC 24V. Use a PS-24N power supply. Amplifier input requirements: AUX; 10K ohm, 0.3V ∼ 0.5V Music source output requirements: Range; 100mV 1.2V, 10K ohm or less Dimensions (H x W x D): 2-1/32" x 3-9/16" x 5-5/8" Weight: Approx. 530g (1.17 lbs.)