Twiga Flexible Duct Designed For HVAC Systems Is Strong, Light Weight, Fully Flexible, Compressible Yet Dimensionally Stable. Application And Benefits : Ideal For All Air-Conditioning And Ventilating Systems In Hospitals, Hotels, Due To High Degree Of Flexibility, Allows Ducting Around Obstacles Where Prefabricated Metal Ducts Would Be Difficult And Costly To Install Available As Bare And Pre Insulated Standard Length - 7 62m (25ft ) Diameter Range - 100mm To 500mm (4 Inch To 20 Inch)