respectively operationally the interposed flexible material 100 a b is then gripped and weighed down in the same manner as shown in fig5 in fig7 8 are presented an longitudinal end view of yet another embodiment for the complemental gripping members of the present invention members 110 and 112 are seen well spaced apart in fig7 while having their inner surfaces 110 i 112 i with configurations which are identical to that of fig1 and 6 however the arcuate outer surfaces and recessed channel surfaces of these members are substantially modified arcuate surface 110 o is interrupted only by the longitudinal channel 110 c of a truncated triangular crosssection which is centrally located in the semi circular outer surface 110 o of member 110 similarly outer arcuate surface 112 o is also interrupted by a diametrically opposing channel 112 c likewise truncated and triangular located central of the semi circular of member 112 elongate channels 110 c 112 c provide the running recess channel for the insertion of the fastening bolts not seen which will lock the seated members together during operation also the central inner surface 109 l 109 r of each member is provided with a transverse borehole 110 b 112 b to receive a fastening bolt not shown in the view of fig8 the members 110 112 are dovetailed to show their complemental seating but without the interposition of the dual ply sheeting of fig6 this embodiment can be used most advantageously on smaller diameter roll up bars so that recesses for heads of fasteners such as in fig1 would not create large flat spots on sides of small diameter roll up bars in the perspective view of fig9 three elongate members 120 122 and 124 like those of fig1 are arranged and aligned as they.