Abstract: A collapsible upright wall extends the height of the sides on the load hauling box on a truck. The collapsible upright wall comprises a fabric which when vertically stretched provides adequate resistance to substantial lateral load. A method of increasing the volumetric capacity of the box on a truck comprises the steps of: a) providing a rectangular frame above, and dimensioned to seat adjacent to an open top side portion of the load hauling box on the truck; b) providing a substantial lift mechanism to uniformly lift the rectangular frame above the box; and, c) providing and attaching an elongate strip of fabric having a top elongate side portion peripherally attached to the rectangular frame, and a bottom elongate side portion peripherally attached to the open top side portion of the box. Then when the rectangular frame is lifted to an upper operable position the fabric is stretched taut and is thereby able to sustain significant lateral load.