The "Frixion Ball Slim 038" is an erasable ballpoint pen with a ball diameter of 0.38 mm, the finest in the Frixion series.
It is an ultra-fine type that is suitable for writing small letters in textbooks. The body is also slim and not bulky, so you can fit many in your pen case.
Equipped with friction ink that turns colorless with temperature changes. The frictional heat generated by rubbing with the erasing rubber on the back of the body turns the ink colorless, allowing you to erase handwriting.
Unlike erasing with an eraser, there is no eraser dust, and almost no residual eraser residue.