Our acid-free Bottle Blue matboards are 4-ply and feature a white core. With an overall size of 24x24, these mats with Circle openings fit perfectly into 24x24 frames and are bevel cut to showcase your 20x20 photos. Actual mat opening size is 19.5x19.5 inches so that it may safely and securely house your 20x20 photo, artwork, needlepoint, sign, etc. This pack includes 1 Single Matboard. Proudly made in the USA by Country Art House!