The CloudFlow 4 has a spoon-shaped nylon blend Speedboard that's stiff, strong and lighter than before. Added to a powerful forward roll to catapult you to new personal bests. The ultra-light woven upper provides breathability and performance that makes picking up the pace easier than ever. CloudTec in Helion dual-density superfoam now runs throughout the shoe. Impact is swallowed, meaning every stride is softer underfoot. What's more, it gives back an ultra-responsive running sensation. And that's crucial to going faster, and staying faster, than you have done before.