I used Koh-I-Noor Rapidiograph pens for most of the 70's & 80's in my career as a draftsman. I had been using the newer artist pens up until I got serous about my pen & ink artwork. This is like finding an ole lost friend. I love these pens! Nothing compares to the quality of the Koh-I-Noor brand. They are the Mercedes of the rapidiograph pens. Great German engineering.
A wonderful set with the finest of tips! Easy to use and nice flow of ink. Definitely need to be willing to take the proper care with them but that is part of maintaining a quality product. Owned the same set in the past (was 'lost' in a move) and had them for many years without any issues so I expect these will be the same.