... inside 2)Bending radius is same as outer diameter Silicone hot air duct for HVAC and ventilation systemMaterial: spring steel ... .high temperature duct, as suction and blast hose, suitable for hot air , blower, exhausting gas, etc. 2.Heat resistant well ... Application: Suction and blast hose, especially suitable: -For transmission hot and cold air. -For printing machines, blowers and compressors. - ...