Exceptional flexibility in this 4.0, more than the 5.0 and more cushioned that the 3.0. Lightweight, supportive flyknit upper and a highly flexible low profile outsole. One layer of upper made entirely of poly yarn for contoured fit. Hexagonal flex grooves cut into the outsole so your foot moves more naturally. Super lightweight and supportive. This is a preloved pair of shoes and will naturally show some signs of wear and use. See photos for specific signs of wear. No structural issues or odors. Smoke free home.