Ideal for fast hikes in warm climates, the X Ultra Mid Aero combines fit, precision, and the aggressive tread all X Ultras have to offer with additional breathability for a more comfortable thru hike on even the most rugged trails.. . Breathable textile and PU coated leather upper. Gusseted tongue keeps out trail debris. Mid ankle rise and Sensifit heel strap heep the boot in place for maximum support. Protective heel cap and rubber toe cap. Textile lining for additional breathability. OrthoLite footbed is comfortable enough to keep you on your feet all day. Nonmarking Contagrip outsole featuring multidirectional, and deep lugs for grip and durability designed for mountaineering.