The XR Series combines the ONE MX with the integrated Trax Rail System that allows for unique and personal customization above your truck bed cover. The RetraxONE XR combines strong, durable polycarbonate with a powerful and incredible scratch resistant matte finish paired with a low-profile patented design that streamlines the overall appearance and provides a firm seal. The XR Series optimizes cargo capacity with the cover open or closed, providing the ultimate versatility in cargo management. The Trax Rail System will work with most T-slot accessories from Yakima, Thule, Rhino Rack, and many more offering endless possibilities. Pairing the Trax Rail System with accessories offers double the cargo capacity. This unique technology frees up the hitch with the ability to mount bikes, coolers, outdoor gear and more on top of the bed cover by combining the Trax Rail system with the t-slot accessories. RetraxOne XR Retractable Tonneau Cover - Matte One Piece Polycarbonate Construction - 2021-2024 Ford F-150 6' 7" Bed without Stake Pockets RetraxONE XR Tonneau Cover 2021-2024 Ford F-150 78.9 Bed