Topic summary
erasers
Extracted from the Wikipedia article Eraser.
Pencil or cap erasers
Originally made from natural rubber, but now usually from cheaper styrene-butadiene rubber, this type contains mineral fillers and an abrasive, such as pumice, with a plasticizer such as vegetable oil. They are relatively hard (in order to remain attached to the pencil) and frequently colored pink. They can also be permanently attached to the end of a pencil with a ferrule.