Holbein's Neri Gomu or Kneaded Rubber is an eraser that does not damage the paper when erasing charcoal or pencils. It can also be a tool for "drawing white" or using it for highlighting rather than "erasing lines" only in a drawing. This can be done by kneading and softening the rubber before use.
Available in different sizes:
No 1 - Small
No 3 - Medium