A manufactured fibre in which the fibre-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of a segmented polyurethane (Federal Trade Commission definition). The soft segment is usually made from polyether or polyester chains and the hard segment is made from urethane or urea units. Spandex, whose name is an acronym of expands, was first introduced in 1958 by DuPont (Lycra®). It can stretch several times its original length and still have nearly 100% recovery. Spandex is one of the most durable elastic fibres available. It is resistant to degradation by sunlight and body oils. Spandex is used for girdles, swimwear, surgical hose and athletic clothes. Chlorine in swimming pools can cause slow degradation of the fibres.