The opening size is 10.5"x13.5" for 11x14 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 blackcore matboards are a 4-ply papermat that provide the aesthetic and design benefits of a black bevel. It can be used for matting photos, art, and needlepoint. Also great for crafts, backboards, signs, children's projects, and school projects.