| For vehicles without rain gutters or a factory installed rack system, the Thule 400XTR Rapid Aero footpack is the strongest way to install a Thule roof rack. The wide base on the Rapid Aero foot makes it extremely stable and the tool free design makes it a snap to install. The 400XTR Rapid Aero footpack is designed exclusively for use with the Thule Rapid Aero load bars, and partnered together the two make an attractive, aerodynamic roof rack set-up that matches the styling of any vehicle. The 400XTR footpack is also compatible with Thule’s simple and secure One Key System lock cores. The installation of the Thule 400XTR requires the use of a Thule Fit Kit that is specific to your vehicle. You can use our Thule Automated Fit Guide to determine the fit kit you need. Also be aware that installing most accessories to the Rapid Aero Loadbar requires one of several Xadapter hardware kits. Thule fairings (870XT, 871XT, 872XT, and 873XT) however, have a special bracket included that allows them to fit either the standard square Thule bar or the Thule Rapid Aero load bar. | 
