Abstract: Each of the links consists of a lamina (1) in the form of a strip which, by way of transverse bends (P1, P2), forms a flat link which is closed by way of pairs of tongues (10) abutting halfway through the thickness of the link, said pairs of tongues being spaced apart; the strip has two openings (3) centrally which border an articulation crosspiece (5) which they themselves form, as well as a lateral articulation extension (7) which is aligned with said articulation crosspiece (5), and each link is articulated to that adjacent to it by means of the pairs of abutting tongues (10) which engage on said articulation crosspiece (5) and on said lateral articulation extension (7), in order that each link is thus staggered in relation to those adjacent to it.