Scents trigger an area in the brain called the limbic system. When stimulated it releases endorphins & neurotransmitters. This can be achieved by direct inhalation or diffusion. YL diffusers are ultrasonic and that is important because it creates negative ions. Negative ions are therapeutic and more importantly they create a mist which creates better air quality. Here are the benefits of aromatherapy and following is our most popular kit that comes with a diffuser. It is half of the retail value just ask me through this website or email@example.com .