The opening size is 8"x10.5" for 8.5x11 print.

 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 with white core. It can be used for matting photos, art, and needlepoint.

How to choose color?  When you checkout, just put a note into the comment area for your color choice. You can mix and match only just choose one color. The available color for this item is White and Black.