Audio-Technica s 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 headworn 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-R900a receiver and either a body-pack transmitter or handheld microphone/transmitter. The ATW-R900a 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-R900a also offers volume control along with AF Peak RF and Power indicator lights.