1,Special design for Eroupe duct flange Standard , 2,L shape, U shape, All wraped duct section with formed connections DUCT LINE-7GDF ... It produces duct from coil stock to ready-to-assembleare “L”,“U”,“Wrap”section with formed connections including Pittsburgh lock , ... beaded and Duplex GDF flange,Automatically bending “L”,“U”,“Wrap”section and seam close,The customer can choice ...