Any question? Please call us at 650-226-8119. The opening size is 4.5"x6.5" for 5x7 print. The mats are beveled cut. Our acid-free cream core matboards are a 4-ply papermat that provide the aesthetic and design benefits of a bright white bevel. It can be used for matting photos, art, and needlepoint. Also great for crafts, backboards, signs, children's projects, and school projects.