This wire all come in 3 x 300mm lengths, strapped to wood so doesn't bend in the post. Sent in straight lengths

Piano wire, or "music wire", is a specialized type of wire made for use in piano strings but also in other applications as springs. It is made from tempered high-carbon steel, also known as spring steel, which replaced iron as the material starting in 1834.

Piano wire has a very high tensile strength to cope with the heavy demands placed upon piano strings; accordingly, piano wire is also used for a number of other purposes, including springs, surgical uses, and in special effects.