RSG Kids & Adult Merino Wool Insulating Boot Socks, 2-Pair or 12-Pair Pack (10 Colors) 4 sizes available. XX-Small normally fits kids 3-5 years old. X-Small is for youth shoe sizes 2-6. Small is men's shoe size 4.5-8 and women's 5.5-9. Large is men's shoe size 8-12 and women's size 9-13. Reinforced for extended wear. Based on the merino wool used, slight variations in fibers/colors are to be expected. Heel forms naturally Extra cushioning and arch support Thermo insulated. Keeps heat close to the body.