An extensible length (5) of material formed from a natural or synthetic elastic polymeric material, has means (56) for securing the length of material to an article, said securing means being located at or adjacent a free end of the length of material, wherein the securing means comprises an end cap (55) secured to the polymeric material. Suitably the elastic polymeric material is formed from strands, and undergoes strain crystallisation. A radial compressive force is applied to the length of material adjacent its end by a compressive sleeve member (51).