The Finer Details The lace lock system attaches to the shoe tongue, so you don’t have to worry about latching it to any fabric. It helps keep your laces in place, so once you tie up, you can focus solely on your workout. Lightweight, breathable mesh helps keep your foot cool yet sports the kind of durability that can withstand scrapes, slashes and quick-drag movements. Dual-density midsole—firm foam on the outside, soft foam on the inside—provides responsive cushioning for lasting comfort for continuous cardio and movements. Full rubber outsole provides durable traction for dynamic movements like cleans and walking lunges. Nike Womens Metcon 9