Audio2000'S Wireless Headset Microphone (ACC6540H-01) Type: electret condenser polar pattern: cardioid sensitivity: -39 3 dB (@ 1, 000 Hz) Output Impedance: &lt; 680 Ohms frequency response: 50 - 12, 000 Hz Power supply: DC 1.5V (external power) connector: 3-Pin mini XLR