Dumbfounded

I've been drawing a lot of storyboards lately, which for me means sketchy pencil drafts which are later inked in and clarified - following which the pencil part is erased, never to be seen by god nor man. Consequently, I picked up a new eraser on Thursday, which I have just gotten around to unwrapping. I bought it because it was the cheapest one in the store, and the store was an art store so I figured I was safe from anything awful (by which I mean smudgy and streaky). Being an art store, however, even the cheap eraser was fancy - a Staedtler rasoplast combi.

It has a blue bit on it which I couldn't make sense of. I intitially thought it was part of the packaging, but no. Different material; different texture. Presumably this is the "combi" in the eraser name. Today, I looked the blue bit up on the website.

It erases pen.

Not erasable pen.

Just pen.

I tried it out.

What does this mean for the world that I can erase pen?