Size Guide:S: US Men 5-8 US Women 6.5-9.5, UK 5-6.5, EU 37-40M: US Men 8-11, US Women 9.5-12.5, UK 7-9.5, EU 40.5-44L: US Men 11-13, US Women 12.5-14.5, UK 10-12, EU 44.5-47 XL: US Men 13.5-14.5, US Women 14-5-15.5, UK 12.5-14, EU 47.5-48.5 *(if you are in between sizes, we recommend sizing up) Say goodbye to tight regular socks that squish your toes together. Say hello to socks that allow for better movement, no sweat between toes, and room to wear toe spacers. Designed to give your toes the space they need to function as they should. Engineered to fit comfortably between the toes with arch compression for all-day support. Material 75% combed cotton, 20% nylon, 5% spandex Returns and Exchanges For health and hygiene reasons some products are not able to be returned for incorrect sizing or change of mind. This includes Toe Spacers, Rock Mat and all socks.