It works with your laces, helping you adjust how snug and secure your foot feels. There's also a clip at the heel, helping with stability as you run over uneven surfaces. Your foot sits on Nike ZoomX, our lightest and highest energy returning foam. It gives you a smooth ride from foot strike through your transition. High-abrasion rubber at the outsole with lugs gives you durable traction. The tongue is even more plush than previous versions.