Grandline Fish Tank Aquarium Algae Cleaning Glass Magnetic scraper It is easy to clean algae and scum off the inside of your aquarium daily. Strong magnetic forces can clean inside by wiping the outside brush. Size: 3.7 x 1.8 x 3.1 inch pefect for small to medium aquariums. The inside brush is floatable. It is easy to pick up after cleaning Money Back Guarantee: refund money for any quality problem in 2 years.