polyethylene or polysulphonates normally the diameter of the wires 2 and 3 lie within the range 0 01 to 0 5 mms the helical elevation 7 provides a greater stability of the meshes of the braided tubular wall 1 i e the parallel wires 2 and the parallel wires 3 will be prevented from moving apart at the crossing points 8 especially in the cross sectional view of fig2 it can be seen that wires 2 and 3 have been deformed locally in a tubular shape the elevation pattern is normally distributed in a regular manner over the tubular wall 1 therefore a specific wire 2 or 3 will have several elevation areas over its whole length within the tubular wall 1 and a much greater stability of the wires 2 and 3 within the braid will be obtained the elevation is further smooth curved i e having a continuous smoothly inclining and declining curvature with the effect that the spring activity of the wires 2 and 3 will be reduced in the areas of the elevations on the other hand the braiding angle between the wires 2 and 3 will be enlarged locally in the area of the elevations which will additionally enhance the mechanical stability of the tubular wall 1 in fact the meshes are immobilized or u201c frozen u201d at the crossing points of the wires 2 and 3 in the area of the elevation by the frozen meshes the tubular wall 1 will obtain an enlarged shape stability which will resist the deforming forces of the body vessel the elevation 7 will also reduce the tendency of the wires 2 and 3 to debraid at the proximal and distal ends 4 and 5 of the tubular wall 1 thus the.