This box is made by Highway Products Inc. The cost on this box is over $1000 by the time you pay the freight to get it to you. Awesome quality, bright heavy treadplate aluminum. Great for Flat Bed farm trucks, construction etc. Go to the manufacturers link to see their products. I also have an HPI Roller Coaster bed cargo slide listed here as well.
The "5th wheel box" is flush-mounted with the bed-rails of your pickup truck. Allowing the front over-hang of your 5th wheel trailer (the part that hangs over your pickup bed) to swing freely without hitting the tool box during sharp turns. Click the manufacturer link to see more pictures of an installed box.