Saim Magnetic Aquarium Glass Cleaner, Aquatic Algae Cleaning Magnet Can be used on glass or acrylic tanks up to 0.12" - 0.23" (3 - 6mm) thickness Strong magnetic forces cause the inside cleaning brush to follow the outside handle. Just wipe the outside, and the inside is cleaned! Dimensions: 1.7" x 1.7" x 1.1"/4.4x4.4x2.95cm(LxWxH); great for Mini to Small aquariums