I discovered these pens 3 years ago and now use nothing else. The novelty of the readability got me to try them, but beyond that they are just great pens. They write smoothly, erase cleanly, are refillable, and come in a variety of colors (for my habit of color coding things), last a decent amount of time and are reasonably priced. I have both the retractable and cap covered ones and haven't used a ballpoint or other gel pen since I found them.