Fast, rugged and ready for whatever wild comes your way, the updated ACG Mountain Fly 2 is here to take you to the top. Over glacial-smoothed granite and up root-twisted trails, Nike reinforced every step with an extended toe cap and mountain-tough rubber sidewalls. The breathable upper helps stop you from overheating, while letting you air out quickly when wet. For extra comfort and support, there's a foam midsole and lightweight plate that runs from the ball of your foot to the heel. Of course, you're going to get dirty out there—that's just part of the fun—but the crag-ready traction (inspired by mountain-biking tyres) has been re-designed to help improve durability and keep you upright and enjoying the adventure.