A Uni-ball pen is filled with clear ink that is stored in the shaft of the pen. When it passes through the ball point, the tip is filled with a coloring agent that will color the clear ink, a particular color of whatever the pen is.
The Uni-ball Fusion pen is a special roller type pen that has a very unique ink system. This pen has a clear ink supply that is visible through its See-through barrel. The clear ink that flows from the pen will then write with color that makes it fun to use.
The Uni Ball is based on German technology that inserts a small round marble into the bottom of a pen. The ink well is housed above the marble, so with every stroke of the writer's hand, the marble's ink is replenished.
