The eraser was held in place by the force exerted by the cylindrical recess of the pen cap. The eraser could be removed, but replacing it required more effort. Erasermates come in blue, black and red ink, with the pen's exterior often matching the color of its ink.
The eraser was held fast by the grip provided by the cylindrical depression of the pen cap. Taking out the eraser required effort, but putting it back needed more force. Erasermates come in various colors, including blue, black and red ink, with the pen's exterior often matching its color.