The Nike Flex Run 21 shoes have a lightweight, minimalist design and are made from at least 20% recycled materials and offer a stretchy, custom fit. The flexibility of the shoe ensures a natural feel so you can find your rhythm. Underfoot cushioning made of resilient foam with a Solarsoft core ensures a soft feel with every step. Stretch recycled material and mesh in the toe cap ensure a comfortable fit and a high quality look.