Interior: Organic Cotton Exterior: Dry-Touch Polyester. DRY TOUCH technology prevents the feeling of sticking, drying faster than other fabrics and keeping the body reliably cool and dry. Breathable technique and thinner seam that provides perfect comfort. Extremely comfortable cast sole. Non-slip heel. Washable on the back at 30 C. Please do not use bleach. Please do not dry in the washing machine. Please do not iron. Do not do dry cleaning.