Kúlupenni er penni sem rúllar ritmiðlinum út í gegnum kúlu framan á pennanum eða áfyllingunni.
A ballpoint pen is a pen that uses tiny spinning balls, made of brass, steel, or tungsten carbide, that release ink onto the paper as you write. The ballpoint pen is very different from its predecessors—reed pens, quills, metal-tipped pens, and fountain pens.
