Audio-Technica system 9 is a four-channel frequency-agile wireless system designed to provide rock-solid performance Along with easy setup and clear, natural sound quality. Featuring sleek, stackable, contemporary styling, system 9 is available in handheld, head worn, guitar, lavalier and body-pack configurations. The system offers four compatible user-switchable VHF channels (169.505, 170.245, 171.045, and 171.905 MHz). each system 9 configuration includes the atw-r900 receiver and either a body-pack transmitter or handheld microphone/transmitter. The atw-r900 is a non-diversity, single-channel receiver with advanced dipole antenna design for extended operating range, which improves operation by providing a ground element in addition to the usual signal element. The atw-r900 also offers volume control along with AF peak, RF and power indicator lights. Features: easy operation and clear, natural sound quality 4 selectable frequency-coordinated VHF channels balanced XLR and unbalanced 1/4 output jacks enable use with a wide variety of audio gear reliable performance and durable construction advanced dipole antenna system for extended operating range specifications: operating frequencies: VHF high band, 169 MHz to 172 MHz modulation mode: FM maximum Deviation: +/-10 kHz dynamic range: >/=90 dB (a-weighted), typical TOTAL harmonic distortion: <1% (at 1 kHz, +/-10 kHz Deviation) operating range: 200' (60 M) typical open range environment with no interfering signals operating temperature range: 40 Degree F (4 Degree C) to 110 Degree F (43 Degree C) battery performance may be reduced at very low temperatures frequency response: 80 Hz to 13 kHz.