Just picked one of these up today. I've been using the 4" once since I got my tank, and wasn't real impressed but it did get the job done. After seeing the scraper in action, I figured I try one out. I have to admit I'm very impressed! The XL is MUCH bigger than I needed for my 90. The magnets are extremely strong. Almost too strong. But it does a SUPER job. Its not cheap, but if you really need to scrape the glass clean, this is the thing you need. I hear through the grapevine that they are planning to put the blade attachment on the large version in the near future. So unless you reall need one, or the XL is the right size for you, you may want to wait it out.