BREATHABLE FLEXIBILITYWith an innovative outsole that expands and contracts with every step, the Nike Free TR Focus Flyknit Women's Training Shoe helps keep your foot flexing naturally throughout your workout. A Flyknit upper delivers lightweight breathability to help keep you cool. BenefitsFlyknit upper offers breathable flexibilityFlywire cables in the forefoot provide dynamic lockdownTri-star outsole pattern expands and contracts with every step for natural comfortInjected unit sole doubles as an outsole for lightweight comfort Nike 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. 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.