I haven't used a pencil this much since I was in school. Almost every place I have been thus far for research has a no pen, pencils only rule. When writing on source documents I also write in pencil. After working for a while, my hand gets cramped. But the Twist-Erase pencil is easy to use and very comfortable. I originally bought the 0.7 but found it too easy to break the lead when pressing down. The 0.9 is stronger but still gives a fine enough line. I keep one with me in my bag, one (or two) on my desk and one in my briefcase. It is definitely a favorite find.