Dai-Ichi Yellow

When I got these in I forgot what made them interesting besides being old, I got really confused when they rattled like they had loose metal in them. Guess what, that's because they have loose metal in them. These have a click leaf instead of a click jacket in them (the top housing could have been a good hint if I was paying attention).

As you can imagine there is no information on these but with calipers it seems like the click is at about 1.5mm and they have somewhere between 4 and 4.5mm of travel (calipers died so I'm measuring manually)