The Black Diamond Tread Aluminum Contractor Truck Box is a slanted, double-level storage solution that mounts on top of your bed rails to save valuable space inside your truck bed. Its lightweight and corrosion-resistant aluminum diamond tread construction assures long lasting use and durability. Each box has two bottom drawers that lock and include adjustable dividers and 100 lb rated slides. Your equipment is secured with four sturdy locking stainless steel compression latches and aluminum continuous hinges. The truck box is built to last with aircraft grade cable lanyards and a watertight gasket system. Lightweight, corrosion-resistant and built to last with a thick .56 in. aluminum construction and black diamond tread finish.