Silent Insulated Duct 1.Specifically produced for low and medium pressure heating,cooling,ventilation Silent Insulated Duct1.Specifically produced for low and medium pressure heating,cooling,ventilation and air congditioning systems2.Have high elasticity and flexibility.They can be easily fitted to oval or connectorsDiameter Range:751200mm(3.5"48")Temperature Range:-30140 Air speed:30m/s( Max.)