The Smell Therapy Kit, also known as a Smell Training Kit, includes four essential oil inhalers that are recommended by scientists & doctors to help you regenerate neural pathways in your nose for those experiencing smell loss (anosmia), reduced smell (hyposmia), or distorted smell (phantosmia). The smell therapy theory refers to the four primary odor categories as the “odor prism.” Just as blue, yellow, and red are introductory color classes. WHAT IS THE ODOR PRISM? Rose Essential Oil - Floral Eucalyptus Essential Oil - Resinous Lemon Essential Oil - Fruity Clove Essential Oil - Spicy These specific essential oils classify the four main odor categories that help you recover quickly from smell dysfunction by stimulating your sense of smell.