Cassia essential oil is extracted from the leaves, twigs, and bark of the cinnamomum cassia tree. As a close relative of cinnamon, it has a warm, spicy aroma and uplifting scent. Add one drop of this essential oil to every 20 ml of water in your essential oil diffuser reservoir. 100% pure essential oil, lab test guaranteed, no fillers. 15 ml bottle. Great for boosting the immune system.