Thank you so much gengar, I think you nailed it!
I tried again and again on Amazon but couldn't find how it was called
While the stupid earplugs usually have a retractable second plug leaving the first one with stereo, the big headsets in SWISS have two monos.
I do not care that much about NC so that was not the issue, but having to carry my own headset takes a lot of space in my bag as I always try to avoid registering any bag.