Thule 636 Sonic XXL Patented Aero Nose Design cuts through the air and reduces drag and noise Patented Rear-Angled Base and expanded vehicle mounting points help maximize trunk and hatch clearance AcuTight Mounting "clicks" when you reach optimal hold to ensure your box is secured to the rack Oversized Secure Lock ensures the box is closed securely and properly prior to driving Dual-Side Opening for loading/unloading from either side of the vehicle