Product Name: TG-500 Aluminum Alloy Roof Turbine Air Ventilator/500mm Aluminum Roof Ventilator/20'' Roof Fans Model NO.: 500mm Certification: ISO, CE, CCC Mounting: Roof Fan Electric Current Type: AC Type: Axial Fan Blade Material: Aluminum Material: Aluminum Fan Ball Dia: 620 Throat Dia: 500 Bearing: NSK Bearing or Ubc Bearing Weight: 6kgs Usage: Ventilation Trademark: TG Transport Package: Standard Export Carton Specification: 500mm Origin: China HS Code: 84145930 Product Description TG-500 Roof Turbine Air Ventilator Aluminum AlloyReference:1. The ball diameter is 620mm.2. The throat diameter is 500mm.3. The base platesize is 650mmX750mm4. Our ventilators are made of stainless steel,Aluminum and fluorinecarbon coated. And we guarantee the usage for 15 years.5.The UBC bearings we use areis importedfrom the USA.6. Ventilators can exhaust the fume and air capacity is about 950-4000 cubic meter per hour.15 YEARS QUALITY WARRANTY !!!!!!!!!!!!TIANCHANG TG TURBINE VENTILATION Co., Ltd is a long history company on main business of rooftop turbine ventilators.The Operating Theory of TG Turbine Ventilators:The undulating vanes lead to smooth rotation by light wind. The bearings at lower and upper position make smooth turns.The motility created by the rotation of the vanes brings the hot air, smoke and wet air up to the roof and exhausts them out.Because the turbine is went on rotating, the fresh air outdoor can enter into the room continually so that the room can ventilate conveniently.The single rotating mechanism will work normally except there is the severe natural damage during 15 years.