Abstract: A reinforcing device to achieve stable fastening points for the inner portion (2) of seismic cables, especially cables that are towed laterally displaced in parallel in relation to the towing vessel and provided with at least two layers of armoring (5,6) intended for absorbing stretch loads on said cable, comprises a fastening means on at least one of the end areas of the inner portion (2), and gripping surfaces for external equipment and shaped with at least two securing chambers (3,4). For assembling the outermost layers of armoring (5,6) of said cable are separated and inserted into one chamber each (3, 4), wherein they are secured to form an integrated connection with said casing (2).