More cushioned than the 3.0 and closer to the ground than the 5.0, the Nike Free 4.0 Flyknit Men's Running Shoe is designed to unleash your natural stride with a low-profile midsole and a lightweight, supportive Flyknit upper. Enhanced Movement Hexagonal flex grooves offer six points of flexibility to let your foot move naturally in every direction. Secondary cuts in the midsole enhance natural range of motion. Natural stride With a 6mm offset between heel and forefoot height, the Nike Free 4.0 Flyknit features a very low-profile midsole and a rounded heel to encourage a more natural footstrike. Support The strong, lightweight Flyknit upper provides a contoured, supportive fit with stretchy polyester yarn. Flywire integrated with the laces delivers added support and an adaptive fit. More Benefits Asymmetrical lacing reduces lace pressure Non-stretch heel knit material for structure and support Moulded sockliner mimics your foot's shape for added support Solid rubber under the toe enhances traction and durability Waffle grip pattern on the outsole absorbs impact and adds responsiveness Product Details Weight: 214 grams approx. (men's size 9) Midsole offset: 6mm 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. In 2002, they examined a group of men and women with pressure-measuring insoles taped to their feet, using high-speed cameras to capture images of each foot in motion. The team spent eight years studying the biomechanics of shoeless running. The results yielded a profound understanding of the foot's natural landing angle, pressure and toe position, allowing Nike designers to build an unconventional running shoe from the inside out.