Golden State Art 16x20 8-ply white mat for 11x14 photo w/ Back + bag, Set of (30) Set of (30) 16x20 8-ply white mat for 11x14 photo w/ Back + bag This item comes with 30 mats, 30 backing, and 30 bags The opening size is 10.5"x13.5" for 11x14 print. The mats are beveled cut with white core and 8-ply thick (about 2.8 mm or 1/8 inch).