I agree that the Victorinox refill is small and useful. They say that the cartridge is pressurized; so, it should write on greasy surfaces. Are these refills as well made as Fisher Space Pen refills?--I do not know. I found mine at a local camping store that has replacement parts for SAKs. Some of the pen types can be seen at http://www.swiss-knife.com/EN/sk/accessories/replacement.html. The one I found did not have the gray plastic part that holds the pen in a knife--just a small brass plug.