I was given several of these by a pro singer. They have revolutionized my music marking because red marks are so much more visible than traditional pencil. And they erase beautifully when the director changes his mind! The pens seem to last me about 2 years each. (I wish it was a little easier to get refills)
The pen tip was very thick considering it said it was a thin tip in the eraser. Made black marks on my paper.