Attipas First Walking Shoes with Socks for Infant/Baby/Toddler's Boys&Girls 80% cotton/ 17% spandex/ 2% rubber yarn/ 1% polyurethane yarn Rubber sole Convenience : Machine washable/fast drying Safety :Tested non-toxic products(TPR 100%) Lightweight & Flexibility/ Machine washable Breathability : Holes release, baby feet's heat Big Toe Box/ The size is measured manually, since there might be some slight differences. Please compare the size chart with your baby shoes and choose the best-suited one. Size Small(US 3.5) 6months - 12 months: Sole Length 4 1/4"(10.8 cm) Size Medium(US 4.5) 12months - 18 months: Sole Length 4 5/8"(11.7cm) Size Large(US 5.5) 18months - 24 months: Sole Length 5" (12.7cm)