Full metal construction provides strong load support Easily adjusts on the bar to accommodate different load widths Compatible with Thule ProBar Evo, Thule AeroBlade, Thule Rapid Aero, Thule Xsporter Pro, Thule Xsporter and Thule TracRac 'XT' Aluminum bars (sold separately) Add Thule Load Straps to secure the load (#521 or #523, sold separately) Simple, tool-free installation This product is not compatible with Thule WingBar Evo