Made of high quality 304 stainless steel with a smooth surface for durability. The bearings are strong enough to withstand wind speeds of 200 kilometers per hour and loads of 100 kilograms. Tightly spaced curved blades keep rainwater out. Suitable for chimneys farms factory roofs ventilation ducts houses warehouses and so on. If you have any questions about the product please do not hesitate to contact us. Suitable for a variety of scenarios and widely applicable