To install the pen's ink cartridge, follow these steps:
1. Remove the pen cap and turn the pen barrel counterclockwise.
2. Grasp the pen grip with one hand and pull out the ink converter or ink bag with the other hand.
3. Take out the new ink sac, align the ink sac interface with the pen holder ink sac interface, and insert it.
4. Check whether the ink bag is fully inserted into place.
5. Turn the pen barrel clockwise to tighten it.
6. For a new pen, you can put the pen tip down and wait for the ink to flow into place. If you are anxious, you can gently shake it and confirm that it is normal before use.
