for everyone looking for a great razor scraper, the Penn Plax is NOT the one. After being convinced by the sales person on the phone, who assured me it would work on my thick glass, I was really disappointed. The picture makes it look big, it's not. Its 2 in by 2in and the razor barely sticks out enough to scrap anything. Even on a thin glass tank, I'm not convinced it would work.
However, after calling the store I got a full refund including shipping. In fact they told me to just throw it away and thanked me for the patronage.
Still looking for a solution or an idea to make me rich!