So you don't want the high tan line of yesterday's running socks? The new Women's PhD Light Micro features high density SmartWool cushioning in the critical impact zones for added protection and durabilty, along with the new SmartFit 4 degree banded fit system for a high performance fit. This sock is ideal for any running event that requires great fit with all day smartwool comfort and performance. Material: 63% wool, 35% nylon, 2% elastic.