The balls are a soil replacement for indoor plants, cut flowers, is suitable with water soluble oils as airfreshener, for decor and for relaxing . The colours don't run, they are non toxic and don't glue together as with some of the copies. They are also environmentally safe as once they breakdown you just add them to the garden which helps conserve water in the soil. We have 10 different colours that you can mix and match to your liking.