The light and flexible Reebok ZigUltra running shoes minimize leg muscle fatigue, allowing you to run longer, farther and faster, with almost no extra effort. This pair of shoes features: Synthetic upper for lightweight support and durability. SmoothFit comfort lining for a perfect fit with no irritation or slipping. Removable PU insole for extra comfort. Dual density midsole for shock attenuation. Spring plate provides great energy return for a soft and springy ride. Zig-zag-shaped sole and transition bridge, absorb heel strike impact and aids toe off propulsion, reducing wear and tear in key leg muscles. Forefoot flex grooves ensure flexibility. Multi-surface rubber outsole for superior traction.