Buyers Products Smooth Aluminum Topsider Truck Box mounts on top of the truck bed rails to save valuable storage space inside your truck bed. Each truck box is crafted with.100 in. thick aluminum and dual, recessed drop doors. Your equipment is better protected from the weather and theft with a locking die-cast compression latch system. The box is built for long life with aircraft grade cable lanyards, watertight continuous hinges, and 1/2 in. thick gasket sealing system.