These pens are really nice and fine, but do require you to know how to handle them properly, and they are held perpendicular from the paper. I have been using technical pens for most of my life and was happy to see that these are still available. I do like the Isographs because you can fill them with pretty much any drawing ink. These are also pretty easy to maintain. I hope that they keep making these because there aren't really that many options anymore for technical pens aside from the Staedtler Marsmatic which is also an excellent pen, and the Kohinoor Rapidograph.

This was a nice addition to my pen set!

It writes very finely and it is easy to fill.