Cruise cross country in Smartwool's merino-made PhD Nordic Ultralight Sock. It thermally regulates your foot, naturally resists odor, and has a long-lasting non-itchy feel. ReliaWool blends nylon and elastane with merino wool for stretch and durability, and the 4 Degree Elite fit uses two elastics for greater stretch and recovery. Mesh zones ensure breathable ventilation, and a seamless toe keeps bunching at bay.