i've previously developed the extra capacity cartridge.
however, due to the added thickness of end sealing component, it was incompatible with some models.
therefore it was stopped.
this time, i've come up with a new end sealing method.
the sealing component no longer interferes with outside diameter thickness.
it is compatible with all my models.
the main component material is acrylic.
both ends are machined to fit and function with my fountain pens.
i've made sure the cartridge will last very long, by making the wall part of the component is thick enough.
refilling can be done with a syringe or spoid.
cleaning is easy, just flush it with tap water.
the end sealing screw is not designed to be taken apart.
it can be made even longer, but for now i will keep it this way.
ink capacity is 2x the standard converter.