They are pieces of cardboard used inside a plastic bags to protect a comic book (illustrated book). They are white on both sides and acid-free. You can purchase them from sources such as Amazon in packages of 100. You fold the fabric in half lengthwise (to about 11 inches and roll up on the board. clip or pin in place. If you measure the fabric before you wrap it, you can pin a piece of paper on the outside. You store the fabric on the narrow end in bookshelves. IOne great advantage is that you can unwrap just the amount you need and cut it for a pattern. Then, record on the paper how much you have removed. Looks great on a shelf.