50% polyamide (tactel) / 40% polyamide / 10% elastane
Spandex or elastane
is a synthetic fiber known for its exceptional elasticity. It is strong, but less durable than its major non-synthetic competitor, natural latex. It is a polyurethane-polyurea copolymer that was invented in 1959 by chemists C. L. Sandquist and Joseph Shivers at DuPont Benger Laboratory in Waynesboro, Virginia. When first introduced, it revolutionized many areas of the clothing industry.