I have two 51's. If I tape them together I guess I have a 102.
I keep going back and forth on which one is my favourite. The "better" pen is one of those ... oh dang, I forget which is called aerometric and which is called vacumatic ... I'm gonna say vacumatc has the push-button at the back end and the aerometric has the squeeze-on-the-side filler ...
... well, the aerometric is the "better" pen. Better ink flow right from the start overnight, and generally, and a nice gold cap, yada yada. The vacumatic takes a little while to get going, and is more likely to have a few moments of dry-nib whenever I pick it up again after a while. Both nibs are "american Fine" in size, I guess.
But dang, that vacumatic has a nib with so much character. It's almost like a tiny little naginata nib. Dang, it's fun to write with.
don't poke the beast... oh no, the 21 is much better.
don't poke the beast
Wow! That ad is as old as I am. And I remember when 51's were still a new pen. A great product from a great State and town. (Janesville, WI.) Too bad there is nothing left of the old company.