Introducing the Endorphin Speed 4 now in fresh winter-inspired hues. Built to conquer any season the Endorphin Speed 4 is more than a race-day shoe. It's equally capable during long, moderate training sessions and sprints to the finish. Thanks to the "just right" combination of winged nylon-plate, SPEEDROLL technology and PWRRUN PB foam, this lightweight running shoe provides the perfect balance of support, rebound and forgiveness.