To the picture gallery
was developed in 1941 as a portable transceiver for US Navy paratroopers. Radio and power source are in a watertight plastic housing. A "Skull Cap" had the headset built in.
At the same time the DAV was introduced as a directional finding issue of the MAB.
Pix of the chassis of MAB and DAV (see picture gallery)
show that they are almost equal.
MAB is a "Squad Radio", a small hand held unit for very local communications. The collection shows all American Squad radios from their beginning (1941) to 1986.
You may also read the article by Alan Tasker :
"U.S. Military Portable Radios"