Fit and Design: No show running socks Patented Sock-Lock Technology delivers targeted compression where it's needed most High-density cushioning ensures maximum comfort at pressure points Anatomically constructed Power Arch technology delivers arch support iWick(R) fibers pull moisture away from feet to keep them dry and odor free Designed specifically for the wearers left and right foot to enhance fit and prevent blisters Seamless construction using the PerfectToe(TM) technology SIZE CHART: Sock Size: Small = Shoe Size: Women's 4-6.5 Sock Size: Medium = Shoe Size: Men's 6-8.5, Women's 7-9.5 Sock Size: Large = Shoe Size: Men's 9-12, Women's 10-13 Sock Size: X Large = Shoe Size: Men's 12-15.5