SMELLY JELLY: These are a non toxic air freshener made to be refreshed. Smelly jellies are made with gel like crystals that can absorb up to 400 times their weight in water, making beautiful gel-like crystals. The water will evaporate over time, but have been known to last 6-9 months. These are great for any living area, office/work stations, lockers, senior living spaces, college dorms, bathrooms, or even in the car. (if using in the car, water will evaporate more quickly). Make the greatest gifts!