This Rack Kit is for truck camper shells and trailers that have roof top sizes no larger than approximately 1165mm/45.9'' (W) x 1358mm/53.5'' (L). The Slimline II Tray mounts to four (6) supplied Feet that slide in to the supplied Track. The 3 x 140mm/5.5'' long tracks can be easily mounted to your canopy/shell or trailer.See the Track installation instructions in the INSTALL tab for further details.