Volume Control Ear Bud (VCEB) NSN: 5965-01-549-6390
This dynamic noise canceling mike type handset is the standard for many PRC-nnn series radios. The noise canceling is accomplished by two design features:
The diaphragm is stiffer than a normal microphone like the H-189 (non noise canceling) (taping the holes on the back will not make much improvement),
There are holes behind the diaphragm so sound arrives from both sides.
We also have the H-350/U
And the H-250/U