Some real difficulties!
I only bought the Mighty Mounts after struggling to get the Yakima Hully rollers installed on my Rav4 (unsuccessfully) and after a couple of e-mails to Yakima, where they finally told me what else I needed. When the Mighty Mounts arrived, it was like putting together a puzzle, but we finally figured out which pieces went together, and boxed up the dozens more that we didn't need. THEN came the challenge of getting the Hully Rollers to work with the Mighty Mounts! The whole thing is probably safe enough (we haven't lost the kayak yet) but it's hard to believe that these pieces were meant to work together.