Polyester and spandex upper. Upper envelopes the foot to help keep debris out. Speed lace system allows for quick-and-easy adjustments, and accommodates a wider foot or higher instep. 4 mm polyurethane insole with Dri-Lex® sock liner featuring antimicrobial technology for a great in-shoe environment. 4 mm EVA midsole provides lightweight cushioning and shock absorption. 4 mm Vibram® rubber outsole provides exceptional underfoot feel without compromising abrasion resistance.