Mag-Float floating algae cleaner for aquariums with round glass up to 5 mm thicknss.+ Easy removal of algae from glass/acrylic surfaces+ No longer knock over decorations, damage corals and invertebrates+ No longer get your hands submerged into the water of the fish tank+ Time/money saver on maintenance+ Large cleaning surface area makes the job quick and efficient+ Stays free of debris+ Can be maintained attached to aquarium surface+ Strong, high-quality neodymium rare earth magnets+ Available for glass and acrylic aquariums+ Can be used on freshwater and saltwater tanks+ Magnet does not lose strength over time+ Easy retrieval of inner magnet+ dimensions: d= 50 mm, height= 30 mm