The [[pneumatic filler|pneumatic filling system]] used by [[Chilton]] is based on compression made by sliding the outside shaft of the pen over a internal metal cylinder which encloses the ink sac like a pump piston. The sliding barrel is equipped with a hole on the bottom that must be hold closed with a finger in the process of pushing it down for compression, but once opened it allow the expansion of the ink sac and the subsequent filling. | The [[pneumatic filler|pneumatic filling system]] used by [[Chilton]] is based on compression made by sliding the outside shaft of the pen over a internal metal cylinder which encloses the ink sac like a pump piston. The sliding barrel is equipped with a hole on the bottom that must be hold closed with a finger in the process of pushing it down for compression, but once opened it allow the expansion of the ink sac and the subsequent filling. |