Our 4-ply matboards are Acid-Free and feature a White Core. With a 8" x 10" overall size, these mats fit perfectly into 8" x 10" frames and are bevel cut to enhance your 6" x 8" photos. Actual mat opening size is 5.5" x 7.5" inches so that the mat may safely and securely house your 6" x 8" photo,