Review on 🐠 Neptonion Algae Scrubber Fish Tank Glass Cleaner Brush - Floating, Scratch-Free, Non-Slip, Magnetizing by Mary Crawford

Works great. The material of the outer part of the scrubber feels like felt. I have a second piece of felt that I place between the handle and the glass for added protection and cleaning. The material on the inside of the scrubber (which does the actual scrubbing) has small bristles, like a thin brush, like the hard side of Velcro. I prefer bristles to flat cleaning material because the bristles don't "catch" debris and risk scratching the glass. The magnet is strong enough to achieve good cleaning. I've found turning the handle like a doorknob to be the most effective method, followed by sliding around corners if necessary. Be careful with the glue.