AKG WMS 420 Headset Set Band M, UHF Wireless System, Frequency range: Band M (826,300 - 831,000 MHz), Diversity system: antenna switching, Up to 8 systems can be used simultaneously, 20 mW Transmitter power, Low battery warning on the transmitter, 9.5"" Receiver, Detachable BNC antennas, Body pack with C555L