Features 1. Special design that conforms to the purpose of human mechanics. 2. Completely sealed with strong magnetic attraction. 3. Perfectly cleans dirt on the aquarium glass surface. Instructions 1. Place the half with the Velcro cleaning pad inside the aquarium and align with the other half with the felt pad outside the aquarium. 2. Please be cautious when handling the magnets. These magnets have very strong magnetic attraction. They should be kept out of reach of children. Dimensions L - 11x6x5 cm M - 8x4x4.5 cm S - 6x2.5x4.5 cm