50 set of Black 12x16 Photo Mats for 8x12 + backing + bags 50 set of Black 12x16 Photo Mats for 8x12 + backing + bags This item comes with 50 single mats, 50 backing, and 50 bags. The opening size is 7.5"x11.5" for 8x12 print with a bevel cut. The mats are beveled cut with white core and 4-ply thick (about 1.4 mm or 1/16 inch).