What is this eraser called?
I have a Staedtler Mars Plastic eraser that is the best I have come across.
Staedtler Mars Plastic eraser is the correct answer. It is the very best eraser. It erases all pencil lines without leaving a grey smudge or a greasy residue and it does not damage paper the same way old fashioned pink erasers damage paper. It's the one used by professional graphic artists, comic book illustrators and fine artists. https://www.dickblick.com/products/staedtler-mars-plastic-erasers/#photos There are other white erasers out there but none come close to the quality of the original.
It might be a plastic eraser
i use a white one with an elphant logo called Koh-I-Noor Hardtmuth , it’s a soft eraser and works really well
Go to an artist supply store and look for it.
There are different art erasers with different names, such as art eraser, gum eraser or kneaded eraser. Look at the photos on the link below to find the type and brand you want.
Hard to tell since a lot of erasers are white. 'Professional' is also a very loose term in the art world since so many professional artists just use what they prefer, which usually requires trial and error. I personally use a vinyl eraser (usually Staedtler) for light sketches (up to HB pencil darkness), and a gum eraser for anything darker. The softer the eraser the better. Kneaded erasers are also commonly recommended by professionals.
Just look where they sell the art pencils and if you can't find it then ask someone for help.