The Pro 7 Dynamic features a low distortion dynamic HC-7 microphone element that is designed to work with most radio rigs, including Kenwood and Yaesu. The HC-7 exhibits a frequency response of 100 Hz – 12 kHz with the -3dB points at 100 Hz and 12 kHz. The traditional Heil speech articulation rise is centered at 2KHz - 4KHz with properly balanced highs and lows. The impedance is 600 ohms. The HC-7 is one of our best microphone elements for speech articulation. Note: To use dynamic mic elements on vintage radios (requiring a high impedance input of 10k to 30k ohms) will require the use of an XT-1 impedance matching transformer.