1. No electricity,energy costing and noise; 2. Easy to install; 3. Warranty:15 years; 4. Long service life. Item Name Natural ventilator & ventilator's foundation Mode 200mm,300mm,500mm,600mm,900mm Material Stainless Steel Warranty 10 years Advatage High revolving speed,clean and easy to maintenance,light weight,high air exhausting efficiency. Packing Carton Usages:1.Industrial workshop/warehouse ...