3 in. diameter x 8 ft. Class 0 air duct with non-crimped ends compresses to 28 in. Ideal for exhaust venting, bathroom venting, range hoods, suspended ceilings, and more Semi-rigid yet flexible for easy installation Fire-resistant 100% aluminum Uninsulated Max. velocity: 5,000 FPM Operating temperature range: -100deg F to 430deg F