The purpose of the 9 TONER by Dr. twentyproject is to provide hydration and to soothe the skin. According to user reviews, it is effective for calming irritated skin, balancing oil production, and delivering a refreshing and hydrating sensation. Users also appreciate its lightweight texture and the absence of fragrance, making it suitable for sensitive skin types. Additionally, the toner can be used as a face mask by soaking a cotton pad with the product and applying it to the skin.