Each pair works with Save Them All to end the killing of dogs and cats in America’s shelters. Available sizes vary. Medium fits USA Men's 8-13, USA Women’s 9-14. Small fits USA Men’s 4-8, USA Women’s 5-9. The socks are made of 75% Organic Cotton, 23% Polyamide, 2% Spandex and have a seamless toe. Machine wash warm and lay flat to dry.