phase following that shown in fig1 in which hole 16 reinforced by a grommet in laminar appendage 15 has green inserted over anchor stud 14 and engaged in the underlying recess present in he lower part of anchor stud 14 fig1 is a schematic representation of the final phase which succeeds the phase represented by fig1 in which the lever arm of the lever shaped connecting grip 5 compresses laminar appendage 15 of fabric 9 against the upper surface of the support the pressure exerted by the lever arm prevents appendage 15 on fabric piece 9 from lifting up and specifically prevents the grommet that reinforces hole 16 from disengaging from the underlying recess on anchor stud 14 to which it is connected preventing appendage 15 from lifting off is important when the piece of fabric 9 is not stretched as is the case whenever elements 1 3 of the support are not planar especially during the extraction phase fig1 a 19 b 19 c and 19 d are respectively profile top bottom and bottom perspective views of articulated button 8 which by resting against the small nose of the contiguous and opposite support element about which said button is articulated ensures that elements 1 2 3 constituting the support are maintained in planar position and which when pressed down frees the small nose and ensures that various.