The Heil Sound Pro 7 is an aviation-style headset designed for amateur radio use in high noise environments. The specially designed foam-gel ear pads provide 26 dB outside noise reduction and provide exceptional comfort. A true dual channel, stereo headset, the Pro 7 Series feature an audio balance control which allows the user to adjust the level of the left earphone to match the right. A unique phase-reversal switch greatly helps the listener “dig out” weak signals. The latest version of the Pro 7 features a monitor jack. The latest version of the Pro 7 features a monitor jack which allows a second operator to plug in headphones and monitor audio. The low distortion Dynamic HC-7 microphone element 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 2K -4KHz with properly balanced highs and lows. The impedance is 600 ohm. The HC-7 is one of our best microphone elements for speech articulation.