I've used them and they do work well for me. The lines stay sharp and the "leads" don't break easily. The eraser thing on the pencil portion does a good job of removing the markings when you want to get rid of the marks. And I do like that you can buy different colored "leads" and use the same pencil. They load like a mechanical pencil, and you just change out the "lead" if you need a different color. But on the downside, they are sooooo expensive. If I were to loose the pencil portion and have to rebuy it, I'm not sure that I could justify the expense. Just my opinion.