If you like to head out on the water with your entire posse, you ve reached the right page of the website. The BigStack rooftop kayak mounts narrow profile carries up to 4 boats on their sides. -SteelCore&rade; construction uses a steel tube frame for superior durability -Top-of-the-line Hullguard padding keeps your kayaks looking brand new -Folds down flat when not in use for the ultimate in rooftop clearance -Locks to crossbar with SKS system (SKS LOCK CORES NOT INCLUDED) -AnchorHead tie-down feature makes it easy to manage straps with multiple kayaks -Fits car rack systems with round, square and most factory crossbars out of the box