I saw this today:
It's a Staedtler Mars Plastic Eraser Refillable Holder.
Well, if you tell me that it can be used to clean corners, yes initially it would but soon its edges would become round like other erasers. How will that be helpful?
If you say that it can be cut to get a new sharp edge, well then it can be done to other rectangle erasers too.
When and why should this one be preferred over the rectangle erasers?