NIKE Men's Flex Experience Run 4 (4E) #749173-003 Synthetic Single-layer mesh and no-sew overlays give lightweight support. Resilient foam midsole is durable enough to double as an outsole. Outsole hexagonal flex grooves promote maximum natural motion. Waffle outsole pistons help absorb impact and add responsiveness. Heel-to-toe offset is 7.2mm.