Two board capacity out of the box (no longer need #504 surf strap to transport 2nd board) Maximum board protection and lateral transport stability with soft, oversized cradle Universal mounting hardware adapts easily to Thule square and Xsporter load bar, Yakima, and most factory installed racks Strong, easy to use straps provide board protection and transport security May require the use of Xadapt3 (80 MM bolts) on some factory applications. This item will require the use of Xadapt3 (80 MM bolts) on our XSporter (421/422) and Rapid Aero Bars