The Thule Load Stops hold gear on your roof rack like bookends hold up all those rows of books in the library. With quick installation, you can get on the road with lumber, ladders, small boats, or any other big gear you need to haul. As an addition, the separately sold Thule Load Straps can pass through the Load Stops to hold everything down securely during your travels.4 inch high load stops help you transfer everything from lumber to canoesLoad straps sold separately CompatibilityThule ProBar EvoPart Number502, 503Manufacturer Warrantylifetime