We set out to give runners a sock that really makes a difference. The Cloud 9 features the most densely padded footbed in its class. It is not a "thick" sock. It fits into running shoes perfectly. The two-size-fi ts-all design has a compression quality that feels therapeutic the moment you put them on. Made with CoolMax® XtraLife™, Cloud 9's will stay with you for hundreds of miles, too. Try a pair and discover a running partner made in heaven.