Scott Franklin kindly sent me these new Franklin-Christoph 14k flex and stub-italic gradient (SIG) nibs that they now sell. I was excited to try these out!  Note that the nibs are $115 and $125 respectively, not $150 as I said in the video – my apologies.

Measurements (note that these nibs can be bought on other models than the 66 Stabilis Desk Pen)
Length (capped): 160.2 mm/6.30″
Length (uncapped): 152.9 mm/6.02″
Length (posted): 175.0 mm/6.90″
Diameter (barrel): 8.3 – 14.2 mm/0.33″ – 0.56″
Diameter (section): 10.0 – 12.2 mm/0.39″ – 0.48″
Weight (all): 24 g
Weight (cap): 4 g
Weight (body): 20 g