This has a yellow grosgrain ribbon in place of a mat.
Wine label poster with ribbon mat in Windsor Ontario
Take a couple of posters and a couple of frames which do not fit and you end up with an expensive job to have mats added at the framers.
Or, you can improvise and use what you have, in my case ribbon. Use the ribbon as a mat to hide the raw edge of the posters. Simply cut and tape neatly at the back, add frame and backing. Hang.