... twisted steel and flat bar above.Front door: Folding door, 4-folds, 4000×4500mm (W×H), galvanized steel frame, with polystyrene ... : Profiled bar beams in the roof to strengthen the room body; wall panel thickness:70mm, width:1150mm, tongue and groove structure, 0 ... and exhaust system(2 sets): Inlet: 2 sets, in total 4×7.5KW double-intake centrifugal fans, model YDW4.5M, air ...