The Gravel 6'' boot is a part of our new ULTRADUTY collection. For the hardest jobs and the toughest environments, you'll never need more than UltraDuty. Built from the ground up with our Ergo design philosophy, the Gravel combines extreme comfort and flexibility with maximum durability. For added protection from the elements we've added waterproofing and 200 grams of insulation to the Gravel. ASTM F2413-11.Waterproof Nubuck Leather Upper. Nylon Mesh Lining. Nylex + PU Foam Sock Liner. Molded PU Midsole. T1200 Outsole. Strobel/Cement Construction. Boot Height: Approx. 6'' Tall.