This is an Altec 639B Birdcage dynamic and ribbon microphone in very good condition with the original "falcon hood" cover. The serial number is 2748. The date inside is 4/56 (see pic). The mic came from an advertising studio in Columbus Ohio, I've had it in my smoke free home studio since 1975.
The mic uses 2 elements to gain multi patterns, the dynamic is an omni pattern and the ribbon is a figure 8, and if you combine them you get a cardiod pattern. There is a switch on the back to adjust the settings.
The 'R' position is the ribbon element only - this is the sound!
The mic works as it should and was wired with a low Z connector when I got it. There is also a 5/8" thread adapter for a standard 5/8" threaded microphone stand.
Cosmetically, this is in very good condition - the ribbon and dynamic elements sound as they should.
Mic stand not included...