WindDiffuser technology disturbs airflow to reduce noise and drag for improved fuel economy SmartSlide, slidable length scale doubles as an under-bar aerodynamic cover, providing quick, no-hassle rack installation TrailEdge design reduces aerodynamic drag by allowing clean air separation from bar SwingBlade end cap pivots open to allow easy access to the T-track for easy installation of accessories Upper T-track with QuickAccess interface allows smooth installation and removal of accessories