US Patent 8939494 Roll up pick-up truck box cover with lock down slats

A roll up cover for a box of a pick-up truck includes a plurality of substantially rigid slats connected by hinge joints. A flexible sheet of material is attached to the top surface of the slats. The hinge joints include a stop which allows pivoting of adjacent slats only in a direction moving the top surfaces of the slats towards each other, to allow the cover to be rolled up with flexible sheet facing inwardly, and with bottom surfaces of the slats facing outwardly, and not vice versa. Side rails are attached to the box of the pick-up truck. A roll rod in each side rail pivots into closed position when the cover is unrolled, with the roll rods engaging the end fittings on the slats, to hold the cover down onto the side rails.