Pets Pal Magnetic Aquarium Fish Tank Glass Algae Glass and Acrylic Cleaner Scrubber Floating Clean Brush 1. Simply drag the no-scratch, felt-lined handle and inside your aquarium, the scrubber follows, cleaning as it goes 2.Available for glass fish tank only 3.The inside brush will not sink into the farthest depths of fish tank as it is floating 4.Super strong magnets for use with 12mm glass thicknesses or under, good for tank for 31-40 gallon 5.Floats avoiding lost magnets on the bottom of your aquarium (An aquarium plant as free gift)