Oregonguywrote a review of Yakima LandShark - Set of 4 on May 29, 2010
Land Sharks mount to both Yakima and rectangular Thule-style bars, but you need Yakima's adapters for factory cross-bars, another $40 to $50, depending on the source. The Land Sharks are somewhat flexible, so they do conform a bit to hull shapes, but not much. Mine are over six years old, mounted on a Thule rack and have had heavy use. No cracks, fading or hardware issues. Something to be aware of is that on most mid-size and some full-size rigs, you can only fit one kayak on the roof using carriers like this. Your rig's width at the ground is one thing. After the cabin area angles in, the factory rack width is even narrower. For two kayaks with these carriers, you'll need the full-meal deal: Complete Yakima or Thule rack system with bars. Check their fit guides.