You can double the volume of ink or paint stored in the pen by removing the reservoir and filling the body. The reservoir provides a double wall of guaranteed protection, which might be what you want, but it does reduce your carrying capacity.
Other nibs you can use in this pen
Nikko Manga G nib fits perfectly
Insert our large nib feed to use the Zebra Manga G, Brause Rose, our Sketch nibs and selected Hunt nibs 22B, 56 and 101
Insert one of our adaptors to draw with a smaller nib, such as the crowquill, Gillott 303 and Principal