This Rack Kit is for truck canopies/camper shells/caps and trailers that have roof top sizes no larger than approximately 1165mm/45.9" (W) x 1156mm/45.5" (L). The Slimline II Tray mounts to four (4) supplied Feet that slide in to the supplied Track. The 1150mm/45.3" long pair of tracks can be easily mounted to your canopy/shell or trailer.See the Track installation instructions in the INSTALL tab for further details.