The Pro 7 offers a feature set that compliments the Heil Sound standard for headset design. Unlike copies of various aviation type headsets, the PRO 7 is not a copy. It brings newtechnology to the headset industry. The 2" thick gel foam ear pads provide extreme comfort for extended periods of time while exhibiting passive noise reduction rated at -26dB, ideal for use in high ambient noise environments. Using technology Bob Heil learned from Paul Klipsch back in the early 70's, the ear cup enclosures were tuned to the free air cone resonance of the speaker cone thus providing very low distortion with maximum voice articulation providing the ultimate sound reproduction for communications. Theexclusive Heil Phase Reversal system (HPR) allows you to acoustically move the signals forward and creates a spatial widening of the sound field. This feature makes it easier to pull a weak signal from a pileup – useful for DxPeditions and contests as well as a stress reliever as your change the phase angle of the program source. A speaker balance control allows preferred level between the speakers.