The Yellowstone is without a doubt One of Oboz longer lasting and more supportive hiking boot. The upper is a smooth finished leather for durability and breathability. This boot features a waterproof membrane to keep your feet dry but also let them breath. The insole is the O FIT insole providing a firm arch support for long lasting comfort.The midsole is made of polyurethane which is lighter and last longer than regular EVA midsoles. Lasty the outsole is a Vibram Megagrip peak outsole for durability and grip!