A favorite of through-hikers and day-trippers alike, the PhD® Outdoor Light packs some serious trail power. Featuring a versatile, multi-sport design, this lightweight hiking style includes Indestructawool™ technology for ultimate durability in high wear areas. And when it comes to comfort, Smartwool pulled out all the stops: the 4 Degree™ elite fit system provides a dialed fit and their signature Virtually Seamless™ toe offers extraordinary comfort in any trail shoe. The Mid Crew height of this comfortable wool sock sits at an ideal height for a low trail boot.