It writes on steel, glass, wood, plastics, plaster, rocks or marble. The extremely durable tungsten carbide stylus needles were during the development phase exposed to a 150 hour test, continuously writing on mild steel. No impact on the needle point could be observed. The pen is powered by compressed air and it has extremely low vibrations at a frequency 2-3 times higher than that of competing pens. The pen is equipped with a medium needle, it can also be equipped with fine and coarse needles, a knife (for wood) and a chisel (for small rocks). One daily drop of oil in the air supply line is all the maintenance required.