Had this pen for a few years which was restored by the previous owner so I never really bothered to pull the section out to check on the sac (and it has only ever seen R&K Scabiosa, so wouldn't have done anything to the sac like an alkaline ink would have). Had it flushed and stored away for a about 2-ish years. Decided to go ahead and remove the section and check on the sac just in case.






I am curious about what was the typical sac size for a pen like this. It's 4.3in capped, 9mm thick, and the inner diameter of the nipple on the section where the sac goes is 4.6mm, the barrel's inner diameter is 7.9mm.



Debating using a PVC sac instead of latex, since the pen is all metal with the exception of the hard rubber section.