While your car may already be equipped with sidebars, the Yakima Whispbar Bar Rack Kit will add immeasurable usability to your roof. And while older crossbars require drilling and other permanent attachments to your automobile, the Whispbar Rail Bars only need the towers that match with your factory side rails. They are easily installed by one person with a few quick measurements and turns of the wrist. What you'll notice is that unlike many factory rack systems, the Whispbar Rails' shape mimics the shape of an airplane's wing. This was specifically designed to move air over the bars smoothly. It not only reduces drag, it also means that you won't hear them whistling on the top of your car.