... 2)Bending radius is same as outer diameter Silicone hot air duct for HVAC and ventilation systemMaterial: spring steel ... 4 meters Specification: 1.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 ...