The SmartWool PhD Light Anklet Running Socks feature a greater volume of wool for enhanced comfort, greater cushioning, and lasting effectiveness over greater distances. The 4 Degree Fit system provides a secure fit for ultimate performance. Ultra Light cushioning helps pad out every step you take without feeling the extra bulk. Mesh zones have been strategically placed for optimal breathability. Higher density wool has been placed in high-impact areas along with WOW Technology for added protection and durability.