Heil Pro-micro Dualheadset W/hc-6.-3db Points Are Fixed At 100hz and 12 Khz with Sensitivity Of-57db At 600ohms Output Impedance (Centered At 1 Khz).designed for Commercial Broadcast Applications. Original Heil Sound The headset is outfitted with the HC-6 element. Designed for commercial broadcast applications, the -3dB points are fixed at 100 Hz and 12 kHz with sensitivity of -57 dB at 600 ohms output impedance (centered at 1 kHz.) The microphone audio for the Pro Micro series terminates into a 1/8 male plug while the head phone terminates into a 1/8 stereo with adaptor The use of the AD-1 series mic adapters allow simple interface with popular transceiver inputs. The adapter is 6 long and has a 1/8 female input jack for the boomset microphone and a 1/4 female that is for the PTT (push to talk) line for the Heil foot switch or hand switch. The 1/4 stereo plug goes into the headphone jack on the transceiver front panel. All Heil Pro Micro Boomsets are shipped with foam windscreen that fits over the microphone. The windscreen does not change the frequency response, just the breath blasts directly into the microphone.