These Air Wick Fresh Waters Scented Oils are designed to provide a consistent long-lasting fragrance to any room through the use of essential oils. Just unscrew cap from fragrance bottle. Insert fragrance bottle into Air Wick Scented Oil Warmer (sold separately) until click can be heard. Plug warmer upright into AC electric outlet. To adjust fragrance intensity， rotate dial on top of warmer unit. The largest dot equals maximum fragrance level.