Lighter and stronger than the previous version, the Nike Air Zoom Structure 21 Women's Running Shoe provides the stability and support that made it a favorite. Softer, lightweight Flymesh material helps keep your feet cool, while responsive Nike Zoom Air cushioning in the forefoot gives you a snappy, springy feeling underfoot. Breathable Comfort The one-piece Flymesh fabric provides more ventilation across the top of your foot. This version of Flymesh has lighter materials that still provide strong support. Secure Feel and Support Combining Flywire with an internal arch band, Dynamic Fit technology provides stability that adapts to you. The top two eyelets are Flywire—strong yet ultralight cables that work with the laces to provide more support as you tighten them. Plus, an elastic band wraps around your arch to help keep your foot from sliding as you run. Superb Stability A wide, flat outsole and two types of cushioning offer stability. Firmer foam cushions the arch side of the foot, while a softer foam cushions the outer side. This creates the right amount of impact protection and stability for your stride.