a thermoformed thermoplastic truck bedliner has a bottom wall with parallel front - to - back ribs which overlies the floor of a truck cargo bed . two side walls extend upwardly on opposite sides of the bottom wall and are joined at a front wall . ribs of a normal height define the load support surface of the bedliner bottom wall , while regions of parallel ribs which are lower in height than the normal ribs define cargo containment regions . the intersection of the reduced height ribs with the normal height ribs defines ridges which restrain escape of cargo in the front - to - back direction , while the bedliner side walls and elevated height protrusions on normal height ribs adjacent to the cargo containment regions restrain side - to - side displacement of the cargo .