Vantech H1 Aluminum Universal Van Roof Rack 2 Bar Low Profile ladder 42"-45" A613 Crossbars are reinforced aluminum with channels for accessories. Max Load capacity of 600 lbs. Accessories: Ladder stoppers, ladder guides and EZ-velcro strap (Aluminum Systems) All Stainless steel hardware Mounting bases are 10 gauge steel and 14 gauge cross bars Total height is 10.5" with 3.5" of clearance under Cross Bar