Grey Felt Wool slippers are completely unique. Made by hand using the best quality materials available, each pair differs slightly for a one-of-a-kind finish. Materials: Felt, Wool. Sole: Rubber. Size Information If you are between the sizes please size up. How to clean my slippers: Never wash your slippers in the washing machine – Our Onaie sheepskin slippers and felt slippers shouldn’t ever go in the washing machine. Instead, hand wash them in cold water with a sponge. Wash the soles with a shoe brush in cold water. Dry them outside, but just make sure to avoid direct sunlight.