This group brings together all those systems that require that the filling takes place through the creation of a depression inside the body of the pen so that the ink is sucked through it. In this case it is generally the body of the pen itself that acts as a reservoir, and can be made of transparent material so as to allow the visualization of the ink level. | This group brings together all those systems that require that the filling takes place through the creation of a depression inside the body of the pen so that the ink is sucked through it. In this case it is generally the body of the pen itself that acts as a reservoir, and can be made of transparent material so as to allow the visualization of the ink level. |