NIKE Flex 2012 RN Womens Running Shoes 512108-013 Synthetic Lightweight sandwich mesh upper for increased breathability and comfort Phylon core is made up of a soft, resilient foam that provides ultraplush comfort and added cushion Abrasion-resistant BRS 1,000 carbon rubber in the heel for heightened durability in this high-wear Phylite carrier delivers a resilient ride and extended durability while reducing the overall weight Molded siping is designed to function as a lateral crashpad for a smoother transition through heel-