The precision Rotring Rapidograph technical drawing pen uses Rotring's unique capillary cartridge. The pressure-equalization system, including the ink helix, is part of the ink cartridge, meaning that every time you change the cartridge you also get a clean new ink helix.
For use on a variety of surfaces, including tracing paper, vellum drawing paper and lineboard.
Replacement ink cartridges and nibs are available.