Abstract: A blank, defining an I beam partition, has a center panel extending at each end edge into a foldably connected substantially L-shaped end panel. The ell extensions of the L-shaped end panels are adjacent one of the side edges of the center panel. At least one of the L-shaped end panels has about the center of its widest portion a cut portion defining an aperture. The L-shaped end panels are bent about their edge foldably connected to the center panel, to extend substantially perpendicularly away from the center panel thus defining an I beam partition to be snugly inserted in boxes. The invention is also directed to a box having the I beam partition wherein each of the L-shaped end panels is snugly positioned adjacent one of the ends of the box to reinforce the ends. The center panel extends between the L-shaped end panels, dividing the box in two portions and cooperating with the L-shaped end panels and the ends to prevent inward and outward movements of the ends of the box.