Manual operation. Waterproof, no battery required. Perfect for various hair styles from thick to thin, short or long, and no matter wet or dry, even to groom hair of animals. Massages your scalp in the shower to ease itchiness and promote blood circulation. Getting a relaxing massage at home and every time you wash your hair. Taking shower with this soft shampoo brush makes your hair and scalp cleaner. High quality and soft hair brush provides you a enjoyable washing experience.