This fountain pen has an eyedropper filling system. To fill, unscrew the grip part, fill ink with the included eyedropper, and screw again the grip section. Now you are ready to write but you need to unscrew the end blind cap.
Eyedropper filling system from Opus 88 has a large ink capacity with a valve that opens and closes flow. Open the valve when you need to write for long session and close it when you want to carry the fountain pen in your bag (or for example on flight!).