12x16 white with Blackcore for 8x12 picture.

Actual opening size: 7.5x11.5".

Our acid-free blackcore matboards are a 4-ply papermat that provide the aesthetic and design benefits of a bright black bevel., Each sheet of mat board has a richly colored front surface with a black core.
It can be used for matting photos, art, and needlepoint. Also great for crafts, backboards, signs, children's projects, and school projects.