adidas Remember what that best-ever run feels like in these shoes built with ultra-cushioned boost and a foot-hugging upper. A revolutionary midsole delivers maximum energy return and doesn't pack down over time. A cage-free adidas Primeknit upper adapts to the changing shape of your foot through the gait cycle and delivers a clean, minimalist feel. The elastic STRETCHWEB outsole flexes to adapt to the way your foot hits the ground.