I read all the complaints about the ink not lasting for this pen. That is obvious if you take its size into account. I am an engineer and need multiple colors of ink, depending on the task that I am doing. My only critique would be the massive size of the clip and it interfering with access to the selector levers closest to it.
**Be advised** DO NOT LEAVE THIS PEN IN YOUR CAR IN THE SUMMER DURING LUNCH. THE INK STOPS WORKING DUE TO THE HEAT. Luckily I read everything and remembered that putting the ink in the freezer reactivates it. It worked again after three days in there. This trick works for writings on paper as well. After you erase it, you can put the paper in the freezer and it will be visible again. This is true for both their pens and highlighters.