The Thule 875XT - Hydro Glide - Set of 2 is designed to aid in loading a kayak from the rear of a vehicle. These rear saddles are typically combined with Thule 877XT - Set to Go saddles which are sold separately. The Hydro Glide hardware will attach to just about any load bars, be it factory installed or aftermarket, there are exceptions so be sure to check the Thule Fit Guide to verify. Once attached, it's simple to make adjustments to match the width of various kayaks. The HydroGlides have pivoting interfaces with the kayak's hull that self adjust as you slide the boat over the smooth marine grade felt. A heavy duty strap with rubber buckle bumper is included along with a tie down for the bow or stern.