Set of 50 pieces of 8x10 Picture Mattes for 5x7 Photos with 50 backing boards and 50 crystal clear sleeve protective bags. Golden State Art Brand Premium High Quality Mattes, Backers & Plastic Clear Bags .The Opening Size is 4.5"x6.5" for 5x7 photo prints. The backing is 4-ply, white on both sides, and core is brown. Each sheet of mat board has a richly colored front surface, a white core and a white backing. It can be used for matting photos, art, and needlepoint. Also great for crafts, backboards, signs, children s projects, and school projects.