I posted a thought that it would be helpful because I have the same thing. You can write electricity to the pen tip and object and melt the metal surface and write figures etc on the metal. · I can write letters etc clearly clearly. You can write even fairly small letters if you get used to it. · It is a feeling that I write with grin and because the pen tip is biting into the target object rather than being able to write it smoothly. Naturally it makes a big difference in the finish with good skill of character. · You can not rewrite (erase). · When you write about 100 characters in a row, it gets hot enough that you can not have the grip part so you need to use it while keeping it cool. Although it has been nearly 10 years since purchase, there is no breakdown. When the pen tip becomes sweet, you can use it with sharpness with rasp.