Ball Pen

Ballpoint pens are produced in both disposable and refillable models.
Refills allow for the entire internal ink reservoir, including a ballpoint and socket, to be replaced. Such characteristics are usually associated with designer-type pens or those constructed of finer materials.
The simplest types of ballpoint pens are disposable and have a cap to cover the tip when the pen is not in use, or a mechanism for retracting the tip, which varies between manufacturers but is usually a spring- or screw-mechanism.
-Wikipedia