supply of supply, installation/erection, testing & commissioning of wind driven turbo ventilators , supply, installation/erection, testing & commissioning of wind driven turbo ventilators on th e existing roof made up of asbestos sheets/corrugated g.i. sheets/toughened aluminium sheets at the sh p floor roof height of 20ft (approx.) with base made up of frp with corrugation matching to existing roof sh eet profile completely in all respect as per the technical features & specifications details given - (1) turbin e diameter 26 inch (660mm) (2) neck/throat 21 inch (533mm) (3) height 18 inch (460mm), (4) vanes (bla des) 42 vanes, al 0.5 own thickness alloy 8011 (5) base ring moc (mounting ring) stainless steel (6) top pl ate moc stainless steel 0.8 mm thickness (7) rotation twin sealed 6203zz bearing with self-lubricating to ensure frictionless rotation even at lowest wind velocity. (8) centre shaft 18mm high carbon steel zinc pla ted. (9) inner arms m. s. with electro zinc plating (10) outer arms m.s. with electro zinc plating (11) numb er of bearing 02 nos. (12) rivets aluminium alloy with washer make: neo enterprises or similar oem quality . [ warranty period: 30 months after the date of delivery ] ]