The OS1st Plantar Fasciitis relief socks help to ease and prevent stubborn heel and arch pain. They provide medical grade support with precise compression for better overall foot function and improved performance. These are designed to hug your feet in with specific seamless left and right construction. These Plantar Fasciitis No Show Socks feature award-winning, patented FS6® compression technology.  Medium fits women's shoe size 7 to 10.5 and large fits men's shoe size 10 to 13.