Ventilation fan

A packing structure for a plurality of ventilation fans, each of the plurality of ventilation fans comprising:

• a frame provided with an opening in a bottom surface thereof and a flange, the frame having a rectangular shape;
• a casing with a fan motor installed therein;
• and an adapter connected to an outlet of the casing, wherein four side surfaces of the frame, except a top surface and the bottom surface thereof, incline outwards and downwards from the top surface to the bottom surface, an area of the opening in the bottom surface is larger than an area of the top surface,
• wherein the packing structure for the plurality of ventilation fans comprises an outer packing carton for packing frames and adapters of the plurality of ventilation fans, and junction boxes, wherein two fixing structures facing each other are disposed inside the outer packing cartons, and the frames are secured in a manner that the frames are secured in a plurality of sets, wherein each of the plurality of sets comprises two or more frames;
• the frames in the same set are arranged longitudinally in an up-down direction where the top surface is directed downwards and the bottom surface is directed upwards, the adapters and the junction boxes are contained inside of a longitudinally upmost frame;
• and
• the frames in different sets are arranged side by side and horizontally.