The Mag-Float Small Glass Aquarium Cleaner, Float-30, is recommend to be used on glass aquariums up to 30 gallons with a surface thickness up to 3/16.Product dimensions: (2 3/8 x 1 3/8 x 1)The Mag-Float cleaners contain special abrasive velcro pads that remove algae from the surface of your aquariumThe Mag-Float floats when the inner magnet separates from the outer magnet. Because you never have to reach into the aquarium, not only can you stay clean and dry, but you also avoid toxic lotions or soap residue on your skin from getting into your aquarium water.Can be used on freshwater and saltwater tanksMagnet does not lose strength over time