Nike Free 4.0 Running Shoe ULTIMATE NATURAL FLEXIBILITY. Combining Nike Flyknit and Nike Free technologies, Nike Free 4.0 for men is designed to set your run free. The lightweight upper has a sock-like fit while the redesigned hexagonal outsole pattern provides the ultimate in natural motion. Flyknit bootie upper provides ultralight support and a contoured fit. Wraparound hexagonal flex grooves integrate with upper to enable more natural motion. Anatomically shaped heel promotes a more natural footstrike. Flywire cables for lightweight support and an adaptive fit.Rib cuff for a comfortable, sock-like fit.Polyester Text.