Endorphin Speed 4 is designed as a racing shoe, but it proves to be versatile enough for both long, moderate training sessions and sprints to the finish line. The perfect combination of a wing-shaped nylon plate, SPEEDROLL technology, and PWRRUN PB foam provides the ideal balance of support, cushioning, and responsiveness. No matter how many kilometers you run, Endorphin Speed 4 is always reliable and fast. About Saucony Endorphin Speed 4 - SPEEDROLL technology - PWRRUN PB midsole material.