Refillable Fountain Pen
Most Fountain Pens are refillable unless otherwise stated in the title of the pen.
Many fountain pens can be refilled via Cartridges or Converter which sucks in fountain pen ink from the ink bottle.
The Majority of Refillable Fountain Pens are pretty simple to refill. If the Refilling process is complex the manufacturer will include instructions on how to refill your Fountain Pen.