The Altec 639 has 2 elements. It is an elaborate studio quality unit which includes a ribbon velocity and moving coil dynamic. A six position screwdriver switch allows the two units to be used separately or in concert to produce a variety of directional patterns. It was used extensively throughout the 40's and 50's. In the late 30's Western Electrics audio business was spun off to become Altec. Other than the name the Altec and Western Electric 639 are identical.
this microphone is also referred to as 'the birdcage'. Classic look and Quality.