1923 MONTBLANC applied for a patent on a rod pump filling system, which used a more sturdy and ink tight barrel without a slit.. The rubber sac inside is compressed by pulling out the inner tube (1) and then pressing it down, simultaneously closing the vent hole (4) with a finger (3). The resulting pressure which compressed the sac (2) is then released by lifting the finger (3) from the vent hole and the sac fills with ink.Though working perfectly the system was not accepted by the German public as the filling movement did not follow the expected direction.