Summary: ***WARNING*** This is probably something your pen manufacturer does not want you to do at the risk you'll do something irreversible to your pen! But really, it's not that big of a deal. Basically, I'm showing you how to remove the o-ring that seals the ink chamber of your vacuum filler pen (in this case, a TWSBI Vac-700 and Pilot Custom 823). What this does is allow you to avoid having to unscrew the back filler knob of your pen.
