Martin Pro-2 Portfolio, 20-Inch by 26-Inch by 1-1/2-Inch The actual unit measures 20x26x1.5 in the interior and 21.5 x 27.5 x 1.5 inch is for exterior. Polypropylene construction rather than the recycled cardboard interior that currently floods the market Incomparable value for student or professional Interior is built with one side with a pocket and the other side with a elastic restraining strap Complete with adjustable shoulder strap, art supplies not included