rotating each other it is possible to eliminate coupling members such coupling shafts for connecting the respective hinge members as it is the case in the second embodiment which will be discussed later in details and thus to decrease the number of parts constituting the hinge mechanisms in the first embodiment the lengths of the inner tubes 16 b and outer tubes 16 a are set to be coincident with the entire length of the longer sides of the slats 12 but it is alternatively possible to mount a plurality of outer tubes 16 a and inner tubes 16 b which are cut to be of shorter lengths of the entire length of the longer side to the longer sides of the slats 12 fig8 to 11 illustrate a shutter panel according to a second embodiment the shutter panel 10 of this embodiment is formed of a plurality of slats 12 connecting tubes 61 of c shaped section serving as hinge members made of aluminum alloy that are mounted on the longer sides thereof at specified intervals and coupling shafts 71 having a shape of a round pipe that are inserted into the connecting tubes 61 rotatably as illustrated in fig8 the connecting tubes 61 are arranged in that connecting tubes 61 mounted to one longer side of a slat 12 and.