I usually get mine from Lowes (closest place). They come two to a package. If the package stays sealed, they last years. If the package is opened, you might as well use both, because the second will be dry before you want to use it. I try to keep several packages of them in the paint cabinet, ready for use whenever needed. I have no idea what the exact design of them is, but appear to be cheese cloth with partially dry orange shellac on them.
They work, if fresh from the package.
Central North Carolina