This is a great adventure boot, with a flex index of 90, 3 aluminum buckles, and an overlap/hike cuff hybrid. Roxa’s proprietary boot liners feature Ultralon EVA components. Ultralon is the most sought after EVA foam for use in high-end ski boot liners. Resilient, heat moldable, light and warm. Simply the best. The ski-hike cuff lock allows for easy striding when open and uncompromising performance when locked.