Aqueon Algae Cleaning Magnets Glass/Acrylic Medium

One piece has a scrubbing side for inside of the aquarium, while the other part magnetically attaches from the outside. Each cleaning magnet comes with one pad for glass aquariums and one pad for acrylic aquariums. The inside scrubber magnet is bottom-weighted that will fall straight down if separated. The bowed bottom design allows the scrub pad to rest above the gravel for easy retrieval while reducing the risk of scratching the aquarium walls. Three different sizes to accommodate various glass and acrylic aquariums.