Rola 59506 Replacement Hardware Mounting Kit for Vortex Rooftop Cargo Carrier Replacement Hardware Mounting Kit for the Vortex Rooftop Cargo Carrier (#59504) from ROLA Includes (1) U-Bolt, (1) Spacer Block, (2) Knobs, and (1) Top Plate Durable construction; built to the same quality standards as all ROLA product