With their capillary structure, the Dr. Vranjes Firenze home fragrance sticks are designed to make the fragrance evaporate gradually and for a long period of time. The set of sticks in combination with the diffuser must be used entirely and in the correct color and size for the fragrance purchased. They are included free of charge with the purchase of a diffuser or refill; however, they can be purchased separately if needed. For more information, please refer to the instructions for use.