The Thule 7533998 Retro-Fit Mounting Kit - For 724 and 725 includes universal mounting clamps, bolts, tightening knobs and complete instructions.  This kit is designed to mount your existing Thule 724 or 725 Flat Top Ski Carriers to factory cross bars racks, Thule Rapid Aero load bars, Thule Xsporter truck rack load bars as well as Thule standard square bars.  Does not work with the 726 Pull Top Ski Carrier.