Because of highway safety reasons the manufacturer recommends professional installation. I wanted roof racks that would hold the most weight. For a 2012 Honda CR-V the maximum is 165 pounds total. A lot of other roof racks are only rated for 150 pounds total. (Not much of an issue for me) The instructions did not cover details for the bolts that attach the crossbar to the left and right "crossbar stays". The instructions also indicated Torx T-30 bolts but they were hex head. Hex wrench was included. I think it worked better to install the bolts into the stays but leave the adjustable "right stay" loose enough to move it. Then install the bolts to the left roof rack rail. Then position the crossbar in place ( I had to flex the crossbar to give it a slight arc in order to get the right stay in place. Then I tightened the right stay to the right rail. Then I tightened the bolts that were the adjustable right stay using the provided allen wrench. Um, I have not used it yet. Tired of carrying things sticking out the sun roof or side window.