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 {TAIL ~ the longitudinal axis} of the extrudate member 
along
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 { TAIL ~ the longitudinal axis } of the extrudate member
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