The Kargo Master 4 Bottle Freon Refrigerant Tank Rack is designed to securely hold four 30 lb tanks or two 50 lb tanks and two 30 lb tanks. These tank racks are built with heavy-duty 1/4"steel bars and 4 tiers of 14 gauge steel shelf plates for structural integrity. Each tier is slightly tilted backward toward the van wall, allowing the tanks to be cradled securely inside the tank rack. The rack is only 13.5" wide which helps to maximize storage space. Nylon straps are included as an extra measure to secure the tanks in place during transit.