VIRTUALLY SEAMLESS COMFORT The Nike Free 4.0 V5 Women's Running Shoe features a nearly seamless woven mesh upper and diamond-shaped flex grooves for a streamlined fit, breathability and natural range of motion. Benefits: • One-piece woven mesh upper for a streamlined fit and ventilated comfort • Synthetic overlays for lightweight, durable support • Phylite midsole that doubles as an outsole for less weight and lightweight cushioning • Diamond-shaped flex grooves for natural range of motion • Rubber outsole pods in high-wear areas for durable traction where you need it 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. 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.