They are manufactured by two hinged expansion joints bound together by an intermediate pipe and related articulations.

They resist pressure thrust caused by internal pressure and allow to compensate remarkable lateral movements on a single plane with very small thrust on fixing points, according to their length.

Moreover, they can also be manufactured with steel bellows or special alloys, according to their use, for example AISI 316Ti, AISI 310, HASTELLOY, INCONEL, AVESTA 904L, MONEL 400, INCOLOY, and with the ends in special materials like CORTEN, A335 P11, A333 Gr.6 and others upon request.