The cap mikes are miniatures transceiver systems built into the Captains' uniform caps, with drop-down microphones (on the left-side of the face) which allow communications between each Captain, The  Captains of Cloudbase and other people.  The caps are activated by an electrical impulse, triggered by the initial radio carrier-wave, directed from the Control Tower on Cloudbase, which activates the electronics and operates the microphone.

Another part of the Captain's communications system are their uniforms epaulettes.  These are-gas-filled "flash-tubes", which light up with a certain colour, coded to the name-colour of whomever the Captain is in communication with.  Cap mikes are also able to make security wave-band changes, as given in each Captain's code-book.