2012 Flow Rival BOA black-tan Unmatched in its class, the Rival is simply the most versatile and adaptable snowboard boot in the park. It’s irie, mon! This Rival delivers a new Articulating instep flex zone with Flow’s updated QuickFit™ system or the BOA® H2 Coiler. Asymmetrical internal backstay and internal harness offer support without overstiffening allowing for easy flex in the park and pipe.