As shown in FIG 3, the first flat portion 3 of the closed sectional structure portion a1 is cut off partially at the end of the extrudate member A1. to define a notch 161 extending {HEAD ~ A1} along the longitudinal axis of {TAIL ~ the extrudate member} 
As shown in FIG 3 , the first flat portion 3 of the closed sectional structure portion a1 is cut off partially at the end of the extrudate member A1 . to define a notch 161 extending { HEAD ~ A1 } along the longitudinal axis of { TAIL ~ the extrudate member }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL