The first demonstrators—pens with transparent bodies—were eye-dropper pens. They were made to showcase the performance of their inner mechanisms. While this is still more or less true today, the term “demonstrator” is now more widely used, covering all writing instruments crafted from clear materials. It’s more a design decision and less a demonstration of what’s inside.
A solid cartridge-converter option would be the Sailor Pro Gear Demonstrator. Made from PMMA resin, it features Nichrome accents and a 21-karat, bi-color, rhodium-plated nib.
We have for sale a brand new Sailor Pro Gear Demonstrator with an H-MF nib. It comes complete with its box, papers, and other inclusions.
