These mighty mounts are used to fit onto the factory roof rack crossbars and enables the user the ability of using Yakima stuff without having to buy the base rack setup. I know these will work on a 3rd gen 4Runner because that is what I used them on. May work on other, but not sure. I have two sets, 1 brand new in the box, and one brand new, but with no box. REI sells them for 30.00 each, I'm asking for 20 shipped. Thanks