There's no mention of this in the article, so be aware there's multiple posts online about QC issues. Rotring quality has been going down over the years, or their name outgrew the actual quality of the product. Current generation of 600s especially suffer from: cracking of the body (0, 1); but most importantly for pens, the joint part that screws into the bottom and upper part of the pen is extremely susceptible to wearing out the thin and fragile upper part's threads, as they are two different metals. So you should be prepared to exercise your warranty if you purchase one.
0. https://www.reddit.com/r/mechanicalpencils/comments/1fzacf9/...
1. https://www.reddit.com/r/mechanicalpencils/comments/1439ru7/...