I have the Flipper but it frustrated me that they put the blade and scrubber pad on opposite sides. If they just put them on the same side you would not have to deal with that nerve-wracking flipping task. Also at some point the blade got bent and enough of the bend carried over to the replacement blades, so only half the blade makes contact with glass anymore. No scratches but I don’t have sand and don’t leave the magnet in my tank when not in use.
So recently I bought the Algae Free (Hammerhead) magnet. Finally someone designed it right and put the scrubber pad and blade on the same side! Also unlike the Flipper it floats and has a nice wooden exterior. The blade isn’t as wide but maybe that helps with contact to glass. It comes with an alternate acrylic scrubber pad and plastic blade so you can use it on either but I use it on glass.