AKG WMS 420 Headset Set Band D, UHF Wireless System, Frequency range: Band D (863,100 - 864,900 MHz), Diversity system: antenna switching, Up to 8 systems can be used simultaneously, 10 mW Transmitter power, Low battery warning on the transmitter, 9.5"" Receiver, Detachable BNC antennas, Pocket transmitter