<span style="font-size: 12pt;">This helicopter helmet Round Mount, also referred to as a "Knurl knob", is used to attach wire or the flex boom to a series of Helicopter Helmets. Will fit all helmets.<br><br>This is the Quick Release version which has a lower profile and twists off the mount for fast replacement of your boom. This is the perfect boom mount when your using two different mics on the same helmet.<br></span>