They are made of %100 cotton and features a smooth inner sponge to be super soft against your child's skin. They do not feature any additional fabric on the inside to keep feet cooler, breathable and feel more lightweight. They’re strategically designed with stretchable slingbacks for a relaxed and secure fit. They allow the feet to move and grow without being constricting. Moreover, they provide enough air while adding some warmth without overheating to make slippers always stay fresh. They can be put in the washing machine. High quality certified cotton holds up very well even after numerous washes, it retains the magical softness that makes it so desirable. Have a soft sole with an anti-grip layer to help with stability and prevent slipping so that kids feel comfortable when they are running around or after bath time.