 to basically rebuild yourself a new toilet from the inside out. All the parts are designed to work together, so you don't have to make multiple trips to the store, which even I am guilty of because I don't have the right part. It even includes specially designed tools to simplify the job. Definitely a DIY project, and you can get clear instructions and videos on the Fluidmaster website. They walk you through step-by-step. They're really good at that, and that's at fluidmaster.com.