Electro-Voice HM2 Unidirectional Headworn Cardioid Condenser Microphone with TA4F Connector for R100/RE-2/RE-1 & Any Telex Wireless, 30Hz-18000Hz Frequency Response Electro-Voice HM2 Unidirectional Headworn Cardioid Condenser Microphone - Black Windscreen - Electro-Voice 3 Year Warranty Generating Element: Electret condenser Frequency Response (1/2" distance): 30Hz to 18000Hz Polar Pattern: Cardioid Sensitivity: Open Circuit Voltage at 1000Hz: 4mV/Pascal (680 Ohms)