• 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 bulb-filler, which might better be termed the bulb-and-breather-tube filler, is the most basic form of a filling system with numerous more complicated variants.

These pens are filled by repeatedly squeezing the bulb.  With each squeeze, air is expelled through the breather tube and out the feed; each time the bulb is released, ink is drawn in by the same route.  This is one of the simplest and most elegant filling systems, whose only real drawback is a slight awkwardness in emptying.  This entails repeated slow squeezes of the bulb, expelling the ink from the nib and feed drop by drop.

Prominent examples of bulb-fillers include the Postal, various economy-line Wahl-Eversharps (a Bantam is shown above), and the French Stylomine.  Most pump-fillers, including Vacumatics, work on the same principle, either adding a device to squeeze the bulb or substituting some other means of intermittently pressurizing the barrel (typically, a reciprocating plunger).