Golden State Art, Pack of 50 16 3/8x20 1/8 Crystal Clear Bag 50 16 3/8x20 1/8 Crystal Clear Bag for mat mattes (Fits 16 x 20" 4-ply mat or 8-ply with backing) Protective Closure (PC) (Adhesive Strip is on the bag instead of flap) All bags are safe for conservation; acid free