Golden State Art, Pack of 10 Black Pre-Cut 5x7 Picture Mat for 4x6 Photo with White Core Mattes Sets. Includes 10 High Premier Acid Free Bevel Cut Matts & 10 Backing Backers Board & 10 Clear Bags Set of 10 pieces of 5x7 Picture Mats for 4x6 Photo with backing boards and bags. This item comes with the 10 pre-cut mats, 10 backing boards and 10 clear bags. The opening size is 3.5"x5.5" for 4x6 print. Color: BLACK The mats are beveled cut with white core and 4-ply thick (about 1.4 mm or 1/16 inch), The backing is white on both sides. The re-sealable adhesive strip of the clear bag is below the opening of the bag instead of on the flap.