I agree with bughunter.
If you can’t find an erasing sheild, drop me a line. I have, it seems, a million of them.
You don’t want a hard eraser because it can destroy the tooth of your paper.
If you are indeed wanting a hard eraser, there are some manufactured with pumice in them. Proceed with caution.
Magic erasers are my favorite. Pink ones are fine for letter writing, IMO, not art. I have seen some that leave pink stains on the paper.
My next favorite eraser is a kneaded eraser. These are better for softer media, such as charcoal and pastel.
two other options:
Staedler makes, IIRC, ‘mechanical pencil’ style erasers that are very thin. I have one that is rectangular and one that is round. These can be hard to find.
Another option is to use an electric eraser. Again, you have to use with a soft eraser and practice using the eraser first. If you bear down too hard on the paper, the tooth will be ruined.