SHIPPING INCLUDED IN THE LOWER 48. These toolboxes have internal design features that make them extra rigid and tough: 1) the larger semi boxes have both a 1/8" "C" channel stiffener bar welded along the bottom front and fully-welded gussets in the sides and corners. (features often ruled out by other manufacturers due to the extra expense); 2) A hefty continuous piano-style stainless steel hinge with a 1/4" pin assures longterm performance; 3) Heavy-duty Hansen? "T-handle" stainless steel locks and mechanisms keep your valuables secure. Doors that will never sag The doors of our double-door, side open boxes close into the frame of the box. That means that they are fully supported during the constant jolting of the road. Our single door, drop open boxes have the hinge mounted to the bottom front of the box, which is extra rigid. Vibration and road stress simply can't warp or damage the hinge.