20x24 Mat for Picture Frame White with Cream Core and 16x20 Opening Size (B222MAT) MAT SIZE: This matting fits a 20x24 frame. (frame not included) OPENING SIZE: This mat fits a 16x20 photo / print. (Actual opening size is 15.5x19.5) Matting Material is Crescent Mat Board. White Finish / Cream Core with White Backing (PH Neutral). This listing includes (1) Custom Cut Mat. (The size selected represents the OUTSIDE dimensions of the matting.)