On the trail, details matter. 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 root-twisted trails, we've reinforced every step with an extended toe cap and mountain-tough rubber sidewalls. Don't worry about pushing your hardest either—the breathable upper helps keep you from overheating and lets you air out quickly when wet.