A true noise cancelling microphone with outstanding sound quality that can withstand the harsh marine environment. A special membrane is used on both sides of the diaphragm which allows air but not water to enter. This allows the microphone to cancel noise that is more then 14 in. away. Racket such as air bubbles and breathing noise are virtually eliminated. This is especially noticed when using a full face mask with an oral-nasal cavity.Designed to be robust the membrane is designed to allow a user to take the mask off at the back of the boat while in the water. In the past microphones being exposed to sea water or to water while cleaning had a short life not so with the Hot Mic. The Hot Mic element can withstand a differential pressure of about 12 feet. In OTSs tests several dives were made to 35 feet and the AGA full face mask with a Hot Mic was removed. After putting the mask back on and clearing it communications were fine.The Hot Mic will give you the finest intelligibility available and last for months with little maintenance.