This Rack Kit is for truck canopies/camper shells/caps and trailers that have roof top sizes no larger than approximately 1475mm/58.1" (W) x 1358mm/53.5" (L). The Slimline II Tray mounts to six (6) supplied Feet that slide in to the supplied Track. The 3 x 140mm/5.5" 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.