The Plast-Combi model is a better all-round eraser than you can find anywhere. It works on pencil and crayon, but its special "blue end" is effective on ball point and fiber-tip pen marks, ink and India ink. It has sharp edges, so it is particularly useful on details.
Made by a German firm by the name of Laufer, famous for its unusual range of natural rubber and synthetic cleaning erasers.
Made in Germany.