This 5-pack of 30 x 40" Bright White Pre-Cut Exhibition Mat Board's from Archival Methods fits 20 x 30" prints. Each board comes fully assembled with a 4-ply beveled window and a 2-ply backing board, which are hinged together with linen tape on the long side of the boards. The bright white, 100% cotton museum board has a centered window for displaying your print. The exhibition mat can be hung in a vertical or horizontal orientation.