Our Acid-Free matboards are 4-ply and feature a White Core. With an overall size of 12" x 18", these mats fit perfectly into 12" x 18" frames. Each mat is bevel cut to enhance your 11" x 14" photos. The actual mat opening size is 10.5" x 13.5" inches so that it may safely and securely display your 11" x 14" photo, artwork, needlepoint, sign, etc.