Inside a first tubular section (5) a smaller second tubular section (7)in a deformable material is housed. The second section is joined by a partition (9) to a portion of the first section. This second section is compressed by deforming under the pressure ...

The thermoplastic material is produced as a rigid closed profile, with a cross section in the form of a hollow body. The material, as used, consists of two separate longitudinal parts (2a, 2b), produced separately by moulding, or extrusion, and assembled t...