Here are some 45-year-old Sennheiser data sheets on the original MD 421 in case anyone's interested.
The MD 421 was widely used as a handheld "on-the-scene" mike by TV news reporters, and was very often seen on camera in Germany back in the day. It was used as a public address and press conference mike as well. It had a heavy construction--at 14 oz., about five times the weight of a typical small condenser microphone. Back when it was introduced, only the most expensive portable recorders had built-in powering for condenser microphones, so a dynamic microphone meant quicker setup and connection, plus operational reliability along with the above-mentioned physical toughness.
The spec sheet reveals something of a marketing shell game in which the microphone is supposedly flat and transparent for full-range music applications but at the same time, has profiled response specifically for speech intelligibility. In truth it is an in-between creature. Its response graph shows a rolloff of 9 dB at 50 Hz and a very broad treble boost of about 5 dB, typical of microphones designed primarily for speech applications and spot miking. An alternate version had a further, variable low-frequency rolloff (not shown on the graph) useful for speech pickup in reverberant environments and/or for very close pickup generally.
There is a modern replacement for the MD 421, but it isn't the same. Because of EU "RoHS" restrictions on the use of materials that are now considered hazardous and/or that pose a problem for eventual disposal, European manufacturers nowadays can't simply replicate their own past products even when they want to. In addition, for decades Sennheiser has been the most high-volume-production-oriented of the European professional microphone manufacturers--the scale of their operations is very large--and the production methods and machines from decades ago have no doubt been superseded several times over by now.
--best regards
Edited later to add Beatles screen capture (I think this was their arrival for their first appearance on the Ed Sullivan show; to me that looks like a Tuchel connector, so it may have been put there by a German TV reporter).