The instrument
The MD-21 Dynamic Microphone was launched by Sennheiser in 1954. From 1959 to 1965, the model was produced as the GDM-121 for Grundig.
Details
Dynamic microphone, omnidirectional characteristic. Transmission range 50 to 15,000 Hz, impedance 200 ohms, sensitivity 1.5 mV/Pa. With tripod thread and table stand. Integrated impedance converter, connection cable with 3-pin diode plug.