NIKE Women's Free 4.0 Flyknit Nike Flyknit construction: Integrates areas of high breathability, stretch and support where you need it most Flywire technology woven into the Nike Flyknit upper integrated with the laces: Provides a dynamic, supportive fit through the midfoot Nike Flyknit tongue is attached on both sides with notches: Allows easy entry Asymmetrical lacing set to the lateral side of the foot: Helps reduce lace pressure Hexagonal flex grooves, hot-knife cut into the midsole/outsole: Offer 6 different flex points for the ultimate in natural motion