Rockville RWM1203VS VHF Wireless Dual Headset Microphone Mic System VHF Wireless Dual Headset Microphone Mic System. High performance wireless microphone system. Includes transmitter with (2) headset microphones. High sensitivity, unidirectional, wireless cardioid microphones. Featuring a dual filter design to limit feedback and interference. Transmitter automatically links to receiver for ease of use. Durable composite microphone construction. Comfortable ergonomic design Operating Range: 100-200(indoor), 65-165(outdoor). Frequency Range: 80MHz-12000MHz. Dynamic Range: 110dB. S/N: 90dB. Operating Temperature: 14F-122F. Frequency Stability: 0.005%. Carrier Frequency Range: 180-280MHz Sensitivity: (S/N=30dB) &gt;2mV. De-Emphasis: 50S. Audio Output Impedance: 600. Audio Output Level.: 0-0.5V. Power Supply: AC110V /50Hz. Current Consumption: 50mA. Audio Out Connector: 1/4 unbalanced Frequency Stability: 0.005%. RF Output Power: 30mW. Modulation Mode: VHF. Maximum Deviation Range: 50KHz. Microphone Mode: Fixed. Pre-Emphasis: 50S. Power Supply: 9V Batt./1.5V2. Current Consumption: 35mA