With a built - in RES(TM) rail expansion system, UltraGroove(TM) makes it easy to attach nearly any Thule(R) or Yakima(R) rack for bikes, kayaks, cargo baskets and more. With or without racks, it's incredibly easy to use and it's covered with a weather - resistant, padded ArmorTek deck laminated to rigid aluminum panels. It opens quickly with just a turn of the lock knob and closes just as easily with a pull on the built - in strap.