From Nike, the Boys' Flex Runner 4 PS Running Sneakers feature:  Mesh upper Elastic straps run behind the heel and across the top of the foot to provide a snug, secure feel. Pull tabs on the heel and tongue work with a stretchy inner sleeve to help make these shoes easy for kids to put on themselves. Slip-on construction Fabric lining Soft, springy foam in the midsole helps cushion their every step. Flex grooves in the outsole add flexibility, helping every step feel natural. Rubber outsole Imported.