Rotring Rapidograph Pens & Nibs

Rotring’s unique capillary cartridge featuring the pressure equalization system.  No need to clean the ink helix because a new helix is replaced with each new cartridge. The difference between Isograph and Rapidograph pens is in the refill type. The Isograph must be refilled with an ink bottle, while the Rapidograph uses a capillary ink cartridge.