This pen was kindly sent to me by Gerrit Speidel, its designer.

Measurements
Length (capped): 137.5 mm/5.41″
Length (uncapped): 127.6 mm/5.02″
Length (posted): N/A
Diameter (section): 10.1 – 10.9 mm/0.40″ – 0.43″
Diameter (barrel): 14.3 – 16.0 mm/0.56″ – 0.63″
Weight (all): 60 g
Weight (cap): 36 g
Weight (body): 24 g