Unfortunately, the Mr. Clean MAGIC Eraser doesn't employ REAL metaphysical Magic or the twisting of the laws of time and space, so it is OK for JWs, who are used to buying in to misrepresented products.
Examples of other misrepresentations that JWs are suckers for include "Faithful and disceet Slaves", "New Light", and a literal place where dead souls reside*.
In the case of the Magic Eraser, here's the secret of how it works: the white pad is a piece of melamine plastic foam. Melamine (melmac) is a pretty hard plastic, and in use the foam breaks down into little tiny hard abrasive particles. The abrasice particles remove a thin layer of the offensive mark. when you scrub with it.
*This one is a real killer, no pun intended. JWs will tell you that the bible teaches that we do not HAVE a soul, but that we ARE soulds. Then, when pressed, they will tell you that when you die, the soul that you do not have goes to a place called Sheol (I think that's in Korea) to await the resurrection. So remember, there is no hell but there is a heaven and when you die the soul that tou do not have goes to a literal place called Sheol (maybe it's not in Korea; it might be on the planet Alcyone).