DYNAMICALLY FLEXIBLE. NATURAL FIT. More cushioned than the Nike Free RN Motion Flyknit, the Nike Free RN Flyknit ULTD Men's Running features a newly designed midsole pattern that expands, flexes and contracts with your foot with every step. Its sock-like upper provides the incredible fit of Flyknit for total comfort throughout your run. UNLIMITED COLORWAY The Unlimited Colorway evokes the limitless potential of athletes in motion, with a spectrum of high-intensity hues and energetic patterns designed to defy description and elude competition. NIKE FREE ORIGINS After learning that Stanford athletes had been training barefoot on the university's golf course, three of Nike's most innovative and creative employees set out to develop a shoe that felt natural and weightless, similar to bare feet. The team spent eight years studying the biomechanics of runners' feet in motion. The results yielded a profound understanding of the foot's natural landing angle, pressure and toe position, allowing Nike designers to build an unconventional and flexible running shoe from the inside out. FLYKNIT ORIGINS Nike Flyknit technology was inspired by feedback from runners seeking a shoe with the snug (and virtually unnoticed) fit of a sock. Nike embarked on a four-year mission with teams of programmers, engineers and designers to create the technology needed to make the knit upper with static properties for structure and durability. Then the precise placement of support, flexibility and breathabilityÑall in one layerÑwas refined. The result is a featherweight, formfitting and virtually seamless upper.