Reebok Men's Zig Pulse Running Shoe 100% Synthetic Synthetic sole ZigTech, one-of-a-kind zig-zag-shaped sole, absorbs the impact of heel strike and propels you forward, while reducing wear and tear up to 20% in key leg muscles SmoothFit seamless liner minimizes rub and irritation DMX Shear cushioning panels for added comfort and reduced heel stress Forefoot flex grooves for added flexibility Removable Ortholite foam sockliner accommodates orthotics