features VHF 210-280MHz, with Echo function, high signal/noise ratio performance offers stable signal transmit and clear sound quality. Features: VHF 210-280MHz band microphone system to avert frequency interface. High signal/noise ratio performance, stable signal transmit and clear sound quality. Dual frequency design, independent volume adjust knob for channel A and channel B. With Echo function for better performance. The effective working range up to 40 meters in the open area.