Pet Magasin Magnetic Aquarium Glass Cleaner - Aquatic Algae Cleaning Magnet EFFECTIVE SOLUTION; your effective solution to tough bacteria inside your fish tanks EASY TO USE; strong magnetic forces cause the inside cleaning brush to follow the outside handle. Just wipe the outside, and the inside is cleaned! PERFECT SIZE FOR SMALL TO MEDIUM TANKS; Dimensions: 3.7'' x 1.8'' x 3.1''; great for aquarium tank with glass thickness of less than 6mm that is less than 35 gallon in volume FLOATS PART; The inside piece floats, so if it becomes separated from the outside piece, it's easy to retrieve.