WindDiffuser technology disturbs airflow to reduce noise and drag for improved fuel economy Secures to roof with Thule One Key locks (sold separately) Cars with sun roof: Due to the racks' low fit on the car, it may not be possible to open the sun roof when the racks are installed. Please check clearance before opening your sun roof. A kit-based roof rack system. Check the Thule Buyer's Guide to find out which roof rack fits your car Smoothly arched bars that fit close to the roof TrailEdge design reduces aerodynamic drag by allowing clean air separation from bar BoxBeam internal structure creates an exceptionally strong load bar Pre-assembled bar and foot system installs quickly Upper T-track allows fast installation/removal of accessories