RoofGoose Vent offers duct riser clamps in 4-Inch, 6-Inch & 8-Inch sizes. Constructed of durable, long lasting 24-Gauge galvanized sheet metal, our duct riser clamp is suitable for all gauges of 4-Inch, 6-Inch & 8-Inch diameter round duct. The duct clamps are designed for vertical installation to support the metal duct going through the roof, though we have found that…