I forgot to mention the filling system of the Hero 616 Fountain pen so I felt I'll just do another post so I could add more pictures.
There is a small ink window, which does nothing to indicate ink level. It only indicates the color of the ink inside and turns clear when the ink is almost out.
It has a permanent squeeze filling system, which comprises a sac which is housed in metal. One fills the pen by pressing on a bar next to the sac, which flattens the sac, forcing air out, and releasing the bar so that ink is sucked in the sac as it expands again. Here's the trick to fill these pen all the way, once you get the pen filled once turn it right side up (the tip pointing to the sky) and press the bar again. Now put the pen's tip back into your ink and depress to take in more ink. Two fills should be enough I tried three and it became overfilled.
