Car Smellies are a unique design. They are a combination of semi precious stones and lava stone. They also come with a Charm to match your style. They are made to hang on your rearview mirror. My recommendation is that you add only 2 drops to the lava stone in the summer, because heat enhances essential oils, and 4 in the winter.
Information on the Aromatherapy Each Car Smellie will have a lava stone. They are very porous and therefore will temporarily absorb essential oils. A few drops my last anywhere from 2 days to 2 weeks, depending on the environment and the quality of the oils used.