SmartWool Women's Phd&reg; Cycle Light Mini Performance Socks, Deep Sea, Medium New 4 Degree Elite Fit System uses two elastics for greater stretch and recovery to keep the sock in place Patent pending ReliaWool Technology in high impact areas provides the longer lasting protection to keep feet comfortable Strategically placed mesh ventilation zones provide ventilation for temperature and moisture management Flat knit durable toe seam for high burst strength Double layer 1x1 ribbed welt