Great extension! I bought the pro version for R$25BRL, and it works for 1 year. The extension works very well with the defined filters. The page where the extension is working must be the only one with the twitter opened, otherwise the work stops to happen. And is necessary to leave the window open and active, nothing complicated. It would be nice if there was the option to filter follow or unfollow active or inactive accounts, that have or not posted in a certain period of time.