Some pre-wound bobbins come with a paper side and when you put them in a machine you take off one of the sides. If you have never used them try them on a project. I love PW and hardly use regular one.
They have a finer thread so more on the bobbin so more sewing less bobbin winding. I have started at a 3 day retreat with a PW b and have use it the hole weekend. and made 6 tops