Our Sport 3 Car Top Carriers are 100% waterproof and attach to vehicles with or without a roof rack. Attach the carrier's straps to a vehicle’s roof rack or use the Car Clips to attach the straps to a vehicle's door frame weather molding. The carrier is made from UV protected PVC Semi-Coated Mesh XT for maximum durability. The intuitive attachment method and simplified design of the Sport Carriers make carrying extra cargo easy.