The Endorphin Pro 4 running shoe is a miraculous feat of engineering: snappy and responsive yet smooth and efficient. Something we achieved by fusing PWRRUN PB and PWRRUN HG together in the midsole – an industry first. A full carbon plate adds longitudinal stiffness and maximum metabolic efficiency. And the silky-smooth heel liner and integrated tongue system makes this marathon shoe feel like slipping on an old friend come race day. Have about 50 miles on these and they are just 1/2 size too big for me. Perfect shape and price!