17x29 Matting for Picture Frame Bay Blue with Cream Core and 13x25 Opening Size (B143MAT) MAT SIZE: This matting fits a 17x29 frame. (frame not included) OPENING SIZE: This mat fits a 13x25 photo / print. (Actual opening size is 12.5x24.5) Matting Material is Crescent Mat Board. Bay Blue 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.)