I received the Flipper Algae Scraper for Christmas and I wanted to do a review for anyone thinking about purchasing one. My glass has never looked so clean. I got the large size scraper and the blade side plows through the coraline that forms crusty spots on the glass. The other side wipes the film clean and polishes the glass very nicely. It has a heavy duty, very strong magnet and won't jar loose when scraping like many of the small magnets do and I have 1/2" glass. It is easy to flip sides and transition the corners. You can buy replacement blades that come in a 3 pack. It is large so it makes quick work of cleaning the glass. I think it comes in two sizes, it has a metal blade for glass aquariums or a plastic blade for acrylic, both included. I think this is a must have for any aquarium.