These are just cool. Heavy-duty suction cups mount reliably to car tops or car glass, to offer a quick easy solution for a single person to load a boat to a car top. Two angle adjustment options allow you to use on most any vehicle. Mount the bar by flipping the lever on the suction cup, then settle the bow or stern of your boat onto the rollers while resting the other end on the ground. Move to the opposite end of your boat, lift and roll, sliding your boat into place on your bars, foam blocks or cradles. Flip the levers on the suction cups when you’re through. Quick, simple, smart.