Aromatherapy CarScenter Diffuser for your automobile. Simply apply 5 to 10 drops of your favorite essential oil or blend of oils on the reusable pad and insert into the Car Diffuser. Plug in the Diffuser into the ligher adapter outlet and within minutes, you will be experiencing the benefits of your chosen oil. Unplug the Diffuser if the red light remains lit after turning off the engine, to avoid draining car battery. A refill pad may be used until it hardens and/or discolors. 12 Volt Socket.