The other day I got a wonderfull ball-point pen from my friend.
It is called "Frixion Pen”.
This pen actually is rarely different from an ordinary ball-point pen.
But one difference is that can erase pen marks.
It is used ink that color varies with changes in temperature and its ink varies colorless to rub by rubber on the top of the pen.
That's very useful for me,and low-priced as well.
It is very convenient,isn't it?