Any question? Please call us at 650-226-8119. This item comes with 50 pre-cut mats, 50 backing boards and 50 clear bags. The opening size is 4.5"x6.5" for 5x7 print. The mats are beveled cut. The backing is also 4-ply. The re-sealable adhesive strip of the clear bag is below the opening of the bag instead of on the flap. Our acid-free whitecore 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.