The upper gets embellished with a Huarache-inspired strap and rubber-striped sidewall that envelops your heel to brace you for movement in any direction Nike Free technology in the forefoot creates flexibility for agility moves and sprints A softer foam core cushions your foot, while a firmer outer layer is durable and stable Rubberised logo on the tongue nods to the Huarache of the early '90s Rubber tread in high-wear areas gives you durable traction The Nike Free Metcon 4 combines flexibility with stability to help you get the most out of your training programme. Updated "chain-link" mesh cools and flexes as you speed through agility drills, while support at the midfoot and heel braces you for your heaviest sets in the weight room.