Pack of 25 5 x 7 Picture Mats for 4 x 6 Photos. These mats are made of acid-free, and pre-cut for immediate use. The opening size is 3.5 x 5.5 for 4 x 6 photo prints. White. 4-ply (~1.4mm or 1/16 inch) mats, both white core and bevel cut. Each items is professional packed and shipped to ensure a safe arrival of your purchase.