Magic erasers are a kind of foam that works as an abrasive for cleaning. In the past, I’ve wondered about how it compares to sandpaper in terms of grit.
I had the chance to test it out against 1000 grit sandpaper in hand wet sanding (cleaning) some vinyl. The eraser left a rougher surface than the sandpaper.
So places that say the eraser is equal to 2000, 3000 or higher grit are probably basing it on lighter pressure and/or effort.
Be careful using an eraser on anything with a finish that might be damaged.