Our acid-free Soft Yellow matboards are 4-ply and feature a white core. With an overall size of 20x20, these mats with Square openings fit perfectly into 20x20 frames and are bevel cut to showcase your 6x6 photos. Actual mat opening size is 5.5x5.5 inches so that it may safely and securely house your 6x6 photo, artwork, needlepoint, sign, etc. This pack includes 1 Single Matboard. Proudly made in the USA by Country Art House!