The Thule 873XT - 52 Inch Extra Large Fairing  offers several benefits to enhance a roof rack system.  The fairing is designed to smooth the air flow over the roof rack.  The fairing reduces turbulence, minimizes wind noise and wind drag.  Many users report that installation of a fairing reduces fuel consumption and pays for itself over the course of a long road trip.  The fairing also looks great and changes the appearance of the roof rack from a utility rack into a sport rack.  Thule fairings come in four sizes to match the width of the vehicle and its roof rack.  It is necessary to check the Thule Fit Guide to determine the proper fit for a vehicle.  The fairing will mount equally well to both Thule standard load bars as well as Thule Rapid Aero bars without blocking the T-Slot, this fairing does NOT work with the Thule AeroBlade load bars.  It's important to note that a faring is not recommend when transporting certain loads such as cargo boxes, canoes, surfboards, paddle boards, and plywood.  It is better for air to flow under the box rather than being directed towards the underside of the load creating excessive lift.