To install a rooftop cargo carrier, place the carrier on the vehicle's roof, fill the carrier and attach the straps as indicated by the instructions for cars with across, lengthwise or no roof rails. Typically, no additional tools are necessary except possibly for pillows or cushions.
Mount the carrier approximately 1 foot back from the front edge of the vehicle, centered from side to side. Fill the carrier as full as possible. If there are open spaces, pack them with pillows or cushions. This keeps the load from shifting, which could damage the cargo packed inside and put excess stress on the straps.
Slide the cross bars into the proper position to stabilize the load. Wrap the short straps around the load, and buckle them to the long straps that run the length of the container. Assemble the provided clamps. If the roof-mounted bars run across the vehicle, then attach the long clamps to the front and rear bars. If the mounting bars run lengthwise, the clamps can be attached to the front windshield and rear window or the hatch jams. For vehicles without roof bars, attach the side-to-side strap clamps to the window jams on the driver and passenger side windows.
Tighten the straps to sufficiently stabilize the load.