Patent ID: 8113489

Claim:
The combination of: top and bottom rails, each rail comprising a one-piece metal member having upright side walls, a top wall joined to the side walls, said top wall having a top surface and a bottom surface, a longitudinal first groove located in the middle of the top surface, a pair of longitudinal first ribs joined to and extended downwardly from said bottom surface, said first ribs being laterally spaced from each other with a space between the first ribs being vertically aligned with the first groove, a bottom wall joined to the side walls below the top wall, said bottom wall having a top surface and a bottom surface, a longitudinal second groove located in the middle of the bottom surface of the bottom wall, a pair of longitudinal second ribs joined to and extended upwardly from said top surface of the bottom wall, said second ribs being laterally spaced from each other with a space between the second ribs being vertically aligned with the second groove, a plurality of first anchor balls mounted on the bottom rail along the length of the top wall of the bottom rail, first fasteners securing the first anchor balls to the top wall of the bottom rail, said first fasteners extended through the first groove, top wall and into the space between the pair of first ribs, said first fasteners being located in holding engagement with the first ribs to provide support for the first fasteners, a plurality of second anchor balls mounted on the top rail along the length of the bottom wall of the top rail, second fasteners securing the second anchor balls to the bottom wall of the top rail, said second fasteners extended through the second groove, bottom wall and into the space between the pair of second ribs, said second fasteners being located in holding engagement with the second ribs to provide support for the second fasteners, and a plurality of tubular members having opposite ends telescoped over the first and second anchor balls thereby connecting the tubular members to the top and bottom rails.