Empire Media MD100. Microphone type: Table microphone, Microphone connectivity: RF Wireless, Microphone frequency response: 30 - 18000 Hz. Receivers AF frequency response: 30000 - 18000 Hz. Transmitter type: Built-in transmitter. Radio Frequency (RF) range: 640 - 699 MHz, Operating frequency type: Ultra High Frequency (UHF), Switching bandwidth: 60 MHz. Battery life (max): 7 h, Battery technology: Alkaline, Battery type: AA