Mat is standard 4 ply material used in Custom Frame shops. Made of lignin-free and pH-neutral materials. Fits into a(n) 18x18 Frame. This mat will fit a 14x14 Photo. Actual opening size will be 13.75x13.75. NOTE FOR ORDERS SOLD BY ArtToFrames ONLY: OPENING SIZE(s) MAY BE CHANGED BY CUSTOMER. Please include your desired opening size(s) by email, or through the contact seller link. If we do not receive a request for a custom size within 2 hours of your order it will be cut with the opening size listed above. Feel free to contact us with any questions you may have.