TWSBI is changing the nibs in their Vac-700 from Bock to Jowo, and in the interim there will be one of each shipped with the pen. If you want to swap the Bock (on the pen) with the Jowo (which comes in a separate nib unit), then you'll want to see this video. It's a little different than when you purchase a TWSBI nib unit by itself (not yet available for the Vac-700), which comes with the grip section of the pen. This nib unit only comes with the nib, feed, and housing, and you'll need to pull the nib out of the housing in order to swap it. It's not hard to do, but there are a couple of little things I needed to point out.