Speed6 - Build for Speed! Developed for quick training runs or racing day, the Speed6 has come out on top in its category in several performance reviews, among them Runner’s World 2017 Fall Shoe Guide, who deemed it ”the lightest and most flexible shoe in this guide”. Speed6 is powered with the RECOIL™ midsole foam - a super lightweight cushioning foam that releases a high rebound energy effect. To enhance the comfort and cushioning properties of the heel impact zone - The SoftFOAM™ area has been added - a heel insert area that has 70% better shock absorbing properties than standard EVA. The black graphic patches on the shoe upper glow in a rainbow of colors when a car’s headlights hit them.