Nike Flex Runner 4 Big Kids' Running Shoes With the Flex Runner 4, you're always ready to race into fun. A flexible, bootie-like design makes it easy to pull on, while stretchy straps help secure your fit. Flex grooves in the outsole let your feet move naturally, helping you find your stride.You spoke and we listened. For the Flex Runner 4, we updated the fit of the midfoot strap and the collar to help make these easy to slip on and comfortable enough to wear all day. Pull tabs on the heel and tongue work with a stretchy inner sleeve to help make these shoes easy to put on.Elastic straps run behind your heel and across the top of your foot to provide a snug, secure feel. Flex grooves in the outsole add flexibility. Multisurface traction works with sturdy foam that wraps around the heel to provide grip and stability when you shift directions.Comfort We reinforced the toe box and used materials throughout to help these kicks stand up to how kids like you play. Soft, springy foam in the midsole helps cushion your every step. Upper - Other Materials, Textile, Lining and Sock - Textile, Sole - Other Materials.