31 which is trapezoid shaped inside the trapezoid structure is the metal sheet 8 also previously described to which a stop screw 27 is fastened the head of which is found within the square block 13 that in turn is located inside the upper track 11 in fig2 and 26 this square block 13 is shown in detail which is made up of polyamide or a similar material and that contains a rectangular floor plan section with rounded corners in order to enable the attachment of this component into the lower 12 and upper 11 tracks the inside part of this piece 13 is hollow and circular and the heads of stop and anchoring screws 27 and 28 are located there the threads of them come out by the lower and upper opening the upper opening 59 of the square block 13 which is in touch with the roof of the upper track 11 has a smaller diameter than the head of the anchoring screw 28 that goes through the roof of the side that makes up the upper track 11 and is threaded in a nut 29 located in the roof of the room the stop screw 27 comes out through the lower opening 60 the circular side of which has a larger diameter than the heads of the stop and anchoring screws 27 and 28 which allows the fitting of the heads of both screws 27 and 28 within the square block 13 the lower side of the panel door contains the same elements arranged between the profile 3.