The New Balance Ultra Low No Show socks rest below the collar of your shoes and produces feet discrete comfort. It includes Silicone grippers and Y-heel pockets to help the low-profile socks stay put. The moisture-wicking NB DRY technology within the socks' poly knit fibers help keep feet cool and dry. The sock features NB FRESH technology to help resists odor. It is made of 98% Polyester and 2% Spandex. Medium fits about women's size 6 to 10 and large fits men's size 9 to 12.