When you want to add some line doodling to letters or shapes, this is a perfect size pen. And again no worries here with these because they will write on everything and not smear.
Used in this layout: be still, the predator is loose
To me the American Crafts Slick Writer is the only one to use when I write on photos. They glide as you write, they don't skip and there's no smudges. Love them!