AMERICAN WWII USAAF THROAT MICROPHONE T-30-S

This T-30 comes with a T-30-S microphone and a M-199 elastic neckband. 

The T-30 carbon throat microphone was the most commonly used tank microphone and was standard for the US Army Air Forces in WWII.

It was made by the Universal Microphone Company, from Inglewood California and has a 2 prong plug, JK-48 jack on a SW-141 push-to-talk switch.

Tanker crews wore this around the neck and it was held with an elastic strap. The 2 pickups themselves, made of rubber, operate via sounds vibrations that are made when the speaker starts talking. This helps the other crew members hear one another over all of the tank noises.