Phoenix or Euroblock terminal connectors

Phoenix - the original modular terminal block

While troubleshooting classroom podium signal path issues, technicians often mention electronic devices and components by their brand name (for example Crestron, Scarlett, Behringer, Inogeni). Sometimes referred to as "Phoenixes", Euroblock terminal connectors are commonly used for disconnectable or pluggable connections, especially in audio, control and electrical applications. They are often used for microphone and line-level audio signals, as well as for control signals like RS-232. 

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Originally developed in 1928.

Context and historical background:

https://en.wikipedia.org/wiki/Phoenix_Contact

https://www.phoenixcontact.com/assets/2018/interactive_ed/101_1118292/index.html#0