Recommended for use on aquariums up to 30 gallons with a surface thickness up to 3/16 " Product dimensions: (2 3/8 "x 1 3/8" x 1 ") Easy removal of algae from glass surfaces. No more flipping over decorations, no more damage to corals and invertebrates No more letting your hands immersed in aquarium water Saving time/ money on maintenance The large cleaning surface makes the work quick and efficient. Remains free of debris. Can be kept attached to the surface of the aquarium. Can be used on fresh and salt water tanks. The magnet does not lose strength over time. Easy recovery of the inner magnet