Cartridge fillers are not a new phenomena in fountain pens. The first ones date back to around the turn of the 20th century. However, those early ones were not entirely practical and prone to their glass and clay cartridges breaking. On the American market, Waterman C/F pens introduced what we have come to know as the first cartridge pens with disposable plastic cartridges. These pens were Waterman's last hit in the 1950s and until the company was revitalized in the 1980s. This rare New Old Stock set is unused and pristine. From the "Fine Flex" chalk mark on the barrel of the pen to 4 unopened, still waxed shut original cartridges, this vintage pen belongs in a museum. Click the headline for close-ups. The steel nib doesn't feel flexi to us, but that is how it was advertised.