An excellent head set microphone. With 8 UHF channels and automatic frequency scanning you always get a great signal! This also works with our over the ear microphone system by Audio technica.  Highly recommended

Operating Frequencies: UHF band, 542.125 MHz to 561.250 MHz          
Number of Channels: 8          
700 SeriesFrequency Stability: ±0.005%, Phase Lock Loop frequency control Modulation Mode: FM          
Frequency-agile Diversity Maximum Deviation: ±25 kHz Operating Range: 200' typical          
UHF Wireless Systems Operating Temperature Range: 40° F (4° C) to 110° F (43° C)
Frequency Response: 100 Hz to 12 kHz