The Darn Tough Run Sock Ultra Lightweight with Cushion is a running sock breathable flex zones in the forefoot and fatigue-zapping arch support. The 1/4 crew height sock features fine gauge knitting and has fast action wicking that keeps moisture away. The all weather performance sock is naturally antimicrobial and guaranteed for life. The merino wool provides breathability and comfort. The True Seamless offers an ultra smooth and invisible feel.