The one and only @amjacobs7 helped me get one of these, and I rushed to fit the cartridge inside the Zento Signature pen body he himself got for me a few months ago — the extra space in the pen barrel was filled with a section from a dried Pilot Hi-Tec-C pen cartridge, which acted as a donor.
First impressions are nothing but amazing; in the world of executive EDC pencils, this simple trick might prove a game-changer; my next step is to compare the Zento-pencil combination with a Kerry and a Zombow Zoom “Superpen” which seem to have similar vibes, and are generally what I consider “standard unit of measurements” for EDC pencils — but I think I already see where this will end.
As a cool byproduct of this transformation, the original Zento cartridge ended in a Porsche-Design Titanium pen originally designed to work with fineliner tips, and the results are, again, spectacular, as if that cartridge had been designed specifically with the PD use-case in mind. Serendipitous star alignments, really.