Single Mat You will receive one single mat. Acid Free, White Core 4-Ply Mats Makes a Great Backing Board Backing and Clear Bags are NOT included with this option. Our Acid-Free matboards are 4-ply and feature a White Core. With an overall size of 22" x 28", these mats fit perfectly into 22" x 28" frames. Each mat is bevel cut to enhance your 20" x 24" photos. The actual mat opening size is 19.5" x 23.5" inches so that it may safely and securely display your 20" x 24" photo, artwork, needlepoint, sign, etc.