Fjallraven x Specialized Prevail Helmet GreenComfortable all around bike helmet, perfect for tough stages in hot conditions. The absence of air blocking foam bridges in the center effectively creates thru air channels, making the S F Prevail Helmet extremely well ventilated.. The innovative AirCage technology works as a suspension bridge and is designed to distribute localized forces throughout the helmet should an impact occur. The Occipital Base Adjustment system optimizes comfort by