The Model 38T is a noise-canceling, hand-held aviation microphone. It consists of an electret microphone element, a microphone amplifier, and a push-to-talk switch enclosed in a rugged, black plastic housing. The 38T is extremely resistant to interference, hum, and squealing induced by 400Hz power systems. Also, the harsh switch popping common to other microphones has been eliminated in the 38T through the use of electronic switching.This 38T handheld microphone (EDMO# 63999-000) is a FAA approved noise cancelling electret microphone that features built-in microphone gain adjustment.