Pre-insulated Duct Flange Accessories including PVC Air Duct Flanges and Aluminum PID Duct Flanges. There are PVC U Section Bar, PVC Tee Connector Flange Joint, PVC invisible Flange Joint, PVC F Section Bar, PVC Covering Angle (PVC Corner), PVC Chair(h) Section Bar. UNT also offers Pre-insulated Air Duct Tool Box, Zinc-coated Steel Angle Bracket (GI Corner), Zinc-coated Steel Hanger, Zinc-coated Steel Shape Disks, Aluminum Adhesive Tape, Tiger Connector,Aluminum Reinforcement Section Bar, Manual Bending Machine for making PIR/PU Elbow.