This roof rack kit is designed for pick-up hard tops/camper cells and trailers with an approximate roof dimension of 1425mm/56.1'' (W) x 1560mm/61.4'' (L). The Slimline II platform installs on the six (6) supplied feet that slide into the supplied rails. The pair of 1600mm/63" rails can be easily mounted on your hard top/cell or trailer. Not returnable or exchangeable.