16x23 Inch Matting for Picture Frame, White with Cream Core and Opening for a 12x19 Inch Photo/Print/Picture (B222MAT) MAT SIZE: This matting fits a 16x23 frame. (FRAME NOT INCLUDED) OPENING SIZE: This mat fits a 12x19 photo / print. (Actual opening size is 11.5x18.5). The reason for the smaller "actual" opening size is to create a .25" overlap on all sides so that the matting sufficiently covers and correctly adheres to the photo or print for proper display. Matting Material is 4-ply Crescent Mat Board; bevel-cut inside opening White Finish / Cream Core with White Backing (PH Neutral). This listing includes (1) Mat Board. The size selected represents the OUTSIDE dimensions of the matting.