• The Basics
• Eyedroppers
• Retracting-nib safeties
• Lever-fillers
• Button-fillers
• Piston-fillers
• Crescent-fillers
• Twist-fillers
• Bulb-fillers
• Pump-fillers
• Vacumatics
• Plunger-fillers
• Blow-fillers
• Touchdowns/Pneumatics
• Snorkels & PFMs
• Capillary fillers

The blow-filler is the simplest pneumatic-filling pen design possible.  One blows through a hole at the end of the barrel, thus emptying out the ink sac.  When the pressure is released, the sac expands and fills.

Blow-fillers were sometimes offered with an accessory rubber bulb, as shown in the picture above, which permitted the pen to be filled in a more dignified and hygenic manner.