Many quality pens take a common refill format, which means the replacement is not necessarily the same brand as the barrel and there is often a choice of ink type within one fitting. Measure or read the old refill before ordering. Ballpoint, rollerball and fountain formats are entirely different and do not interchange. See executive ballpoints, fountain pens and rollerball refills.

Parker fountain pen with bottled ink and refill cartridges arranged on a bright professional desk with coffee and stationery.