This version of the Nike InfinityRN 4 still provides a plush and smooth ride, with the new ReactX foam delivering more support. The revamped Flyknit upper and wider toe box help your foot feel stable and secure. The more cushioning that you have underfoot, the softer and more comfortable your running experience can be. Cushioning helps soften impact as your feet hit the ground. ReactX foam gives you an incredibly smooth feeling, helping you push your limits. The more supportive the shoe, the more stability it can give to your natural stride. A combination of tuned support and intentionally placed cushioning helps you feel secure with every step. A curved outsole helps your foot rock smoothly from heel to toe and through your stride to footstrike. It makes every step feel more natural and adds efficiency to your run, helping you waste less energy as you hit your stride. A new internal Flyknit fit band (like a rubber band around the middle of your foot) offers elastic, secure support. The more responsive the shoe, the more energy return you can get back with each step. Whether you want to run a little bit faster or with a little less effort, responsive shoes help give you slightly more spring in your step to get more out of your run. ReactX foam gives you +13% energy return compared to React foam, helping you stay fresh and bouncy during your run.