SET of 10 - GREATPACK 8x10 Black Double Mats and Backings - Fit 5x7 Photo Art This is a set of ten 8x10 double black mats with beveled cut openings and matboard backing for each. The opening size is 4.5" x 6.5" to fit 5"x7" image sized photos or art. These are acid free neutral ph mats with a white core which does not yellow over time like many regular core mats available. These same high quality mat packs are available as both single and double mats in 5x7, 8x10, 9x12, 11x14, 12x16 and 16x20 sizes in white, antique white and black.