The Schmidt PRS cartridge rollerball system, complete with chrome grip section, uses short international fountain pen ink cartridges to follow the functional principle of a fountain pen. The low wear ball tip has been developed specially to achieve unparalled durability allowing multiple changes of ink cartridge whilst maintaing writing performance.
You can convert any fountain pen using an Schmidt FH41 or FH241 nib unit to an ink cartridge pen by replacing the nib unit with a PRS unit as they all use a common thread system.