RCA UZ 4083 MIKROFON vintage 1929

not rare, very rare unidentified American made microphone, either RCA or WESTERN ELECTRICS, (if any of you experts know something about it it would be fantastic) .. very original object still like its mother made it, never touched or serviced, inside there are still its original valves, and behind the valves still other components, therefore complete... I await more precise information from those who know it to then define a real and reliable economic value... thanks...