The Nike Free Trainer 3.0 Shoes Cool Grey/Black/Volt blends a supportive, breathable upper with a flexible outsole for a barefoot-like training experience. Dynamic Fit technology uses Flywire cables to wrap the arch for a glove-like feel.FLEXIBILITY AND DYNAMIC SUPPORTBenefits TPU mesh upper simulates the toughness of metal for extreme durability and ventilation Dynamic Fit technology wraps the midfoot for a glove-like feel Straps anchored under the foot that connect to the laces allow for a customized fit Phylon midsole for lightweight cushioning Deep flex grooves for natural flexibilityNike Free OriginsAfter 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 and flexible running shoe from the inside out....The Nike Shoes more colors