dualFX® technology by LYCRA® brand was developed in response to market demand for high-stretch denim fabrics that keep their shape. It is based on several patented technologies from INVISTA related to dual core yarns and bi-component yarns. Typically, as fabric stretch increases so does the tendency for fabric growth or shrinkage. By combining LYCRA® fiber and LYCRA® T400® fiber together in one fabric, you get the best of both worlds — the high stretch of LYCRA® fiber and the excellent recovery power of LYCRA® T400® fiber. So consumers can have super stretch jeans that fit all day, every day.