The Audio-Technica ATW902A System 9 Wireless System includes an ATW-R900a receiver and ATW-T902a handheld dynamic unidirectional microphone/transmitter. This system also includes an AT8456a Quiet-Flex stand clamp. The ATW-902A system 9 frequency-agile VHF wireless handheld transmitter and mic from Audio-Technica is a frequency-agile, single-channel transmitter with a unidirectional dynamic capsule. This means that you can select any one of the four frequencies (169.505, 170.245, 171.045, and 171.905 MHz) and use up to four systems 9 wireless systems at the same time, if each system is set to a different channel frequency. This system has a 200 feet-typical operating range and can operate in temperatures ranging from 40-degree-F to 110-degree-F. The Audio-Technica ATW902A System 9 Wireless System offers an 8-hour (alkaline) battery life depending on battery type and use pattern.