The Audio-Technica System 9 handheld wireless system is a four-channel frequency-agile wireless system designed for solid performance along with easy setup and clear, natural sound. The system offers four compatible user-switchable VHF channels (169.505, 170.245, 171.045, and 171.905 MHz). The ATW-R900 is a non-diversity, four-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 receiver also offers volume control along with AF Peak, RF and Power indicator lights. The ATW-T902 transmitter features a dynamic unidirectional microphone capsule for excellent gain before feedback and sound quality. It operates using standard AA batteries for extended use of up to 8 hours (with alkaline batteries).