VEVOR Roof Rack Basket, 1630 x 1270 x 105 mm, Universal Rooftop Cargo Carrier with Two 900 x 1000 mm Cargo Net, 68 kg Max Car Top Luggage Holder, 4.1 in Fence, Anti-Rust Alloy Steel, for SUV Truck Car

You only need 2 crossbars (roof racks) to mount this carrier, as the package includes 4 universal U-bolt mounting clamps designed specifically to secure onto a standard two-bar roof rack system. If this answer does not resolve your current issue, please contact us again for assistance.