Flexible   duct  coated L=10ml with internal antibacterial/anti-mold sanitized treatment, thermo-insulating coating and external protection with resin film. Built-in spiral in harmonic steel flo. Extra coating in 25mm polyester fbra wrapped with aluminized film layer. Working temperature: -40°C/+100°C (-40F/212F). Color: inside grey; outside aluminium. Fire reaction for Italian standard: - class 1 (DM 26/06/84); for European standard: - class EN B-s2, d0 (13501), class EN B-s1, d0 (13823). Max air speed: 20 m/s. Minimum bending radius: 1,2 ÷ 1,8 times the diameter (depending on diameters).