Comfortable over a wide temperature range, these Injinji ankle-height, split-toe socks allow you to wear your flip-flops year round. Anatomical Molding SystemTM conforms to your feet to allow blood and air circulation Individual big-toe sleeve allows you to comfortably wear these socks with flip-flops and other thong-style shoes 3-ply flex construction prevents sock movement while increasing wicking and circulation Precisely stitched Vector Heel prevents bunching and creates a comfortable fit Double-layer welt top maintains shape for long-lasting performance and support Knitted with melange finely combed cotton for a naturally soft and breathable feel Sizing is as follows: S fits women's shoe size 6 - 8.5 / men's shoe size 5 - 7.5 M fits women's shoe size 9 - 11.5 / men's shoe size 8 - 10.5 L fits women's shoe size 12+ / men's shoe size 11 - 13.5 XL fits men's shoe size 13.5+