The Staedtler Mars eraser is a classic eraser that's used in the office, schools, the drawing board, and just about everywhere there's a pencil needed in the scene. It's one of the most popular brands of erasers in school (along with the Pentel Hi-Polymer eraser), and I can see why because of its quality, durability, and reliability to get you through the toughest of exams.
The first thing you notice are small trojan heads (the company's logo perhaps?) printed on the eraser. The sleeve is blue with "Staedtler Mars Plastic" printed in white. The sleeve is easily damaged after normal wear and tear, and when the eraser get smaller, cutting off part of the sleeve might be a good option.
There's not much to say about it, really. It's a reasonably large eraser that has gotten me through more than a semester of school. It erases very cleanly with little or no pencil remains showing (depending on the type of lead you're using). However, it does leave quite a bit of residue, much more than the Tombow Mono does. It's a bit of a hassle to brush the shavings off, since some of them are so small.
Performance-wise, it erases HB lead quite well and very cleanly, leaving no marks or traces behind, same goes for the blue lead. For the 4B, since the lead is softer, the eraser smears it a bit before being able to erase. I'm guessing that with softer leads, it's going to smear more and leave a bit more remains.
Overall, this eraser is very durable and it's great for school/office uses. Depending on how much you use it, it will last you a couple of months. If you don't mind having to sweep off eraser shavings every time you erase, then go ahead, go to your local stationery store, and buy one of these. It should only set you back about 50 cents.