The opening size is 12.5"x18.5" for 13x19 print + backing board + clear bag

 Our acid-free whitecore matboards are a 4-ply papermat that provide the aesthetic and design benefits of a bright white bevel., 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.

Other color is also available upon request.

Quantity 1 = 10 mats and 10 backing.