The solid metal 'nib' consists of a metal alloy, that leaves a mark on most types of paper. If you use the sort of paper typically used in printers and photocopiers, the metal pen leaves a mark that looks as if it was made by a pencil. However the line will not smudge, and cannot easily be rubbed out. This has a number of advantages, especially if you are left handed!

Since there is no ink, there is nothing to dry out, so the metal pen will work just as well in 25 years time as it does today.

I would guess that in time the nib would begin to wear down, as you are leaving a small amount of metal on the page. However this has got to be a much slower process than with a pencil, which wears down pretty quickly. The designer tells us that if the point becomes slightly blunt, you can 'sharpen' it again using sand paper.

The metal alloy nib is relatively soft, so it is advisable not to drop the metal pen onto a hard surface. Otherwise you may snap the nib off.