Sorry That is not an acceptable Definition. Read My Post about how Prill is made. Read the Link I have to Wikipedia. There in no way they talk about Slow release. What they talk about is How Prill is made and what it is. ""A prill is a small aggregate of a material,"" HELLO WHAT IN A GRANULE??? other than a small aggregate of material. All Prill is a Granule but all Granules are not made by a Prill tower. BTW Did your Girl Friend give you that screen name?? I guess we all can't be Porn stars.