This pencil uses a soft 9mm water soluble chalk to make a line you can see that isn't too thick. The chalk is firm enough not to break as you draw on fabric—unless you push too hard. You know how that goes. I use this pencil when I am drawing very small or fine shapes.
You might want to order two pencils so that you don't have to keep changing the color of chalk as you work, or order the Sewline Trio.