Outer fabric: Sherpa is a loop fabric with a woolier feel. Interior fabric: Same as all the other slippers, the interior lining is very soft! Composition: 0-3 and 3-6 months: 100% polyester 6-9 months to 36-48 months: Exterior 100% polyester – Sole 60% nylon 40% polyurethane Care: Machine washable. Machine dry or lay flat to dry for synthetic suede soles. To avoid having small lint of different colors on the slippers, it is best to wash them with similar shades. Size chart: -0-3 months = 11 cm ( velux sole) -3-6 months = 12 cm (velux sole) -6-9 months = 13 cm (non-skid sole) -9-18 months = 14 cm (non-skid sole) -18-24 months = 15 cm (non-skid sole)