Dynaduck fabric, with 8.5 oz army duck cotton canvas and a water repellent, mold and Uv resistant finish. Double-stitched seams with reinforced corners for added strength. Galvanized steel poles for durability and maximum resistance to harsh weather. Proprietary shock-absorbing grounding system to stand up to harsh weather conditions. Pre-installed heat resistant silicone-coated stove jack with a 5-inch pre-cut pattern.