The Sennheiser MD 421 was released in 1960 to much acclaim, with a very tight cardioid polar pattern that borders on "supercardioid" at many frequencies and a clear, present sound that was far superior to most dynamic mics of the era.

The MD 421-N model features a 3-pin DIN connector and a switchable high-pass filter that goes from "M" for music (full bandwidth) to "S" for speech (low frequencies attenuated).