It's one of the larger V69 cases at 31.5mm, 16mm lugs. Also uncommon for this already uncommon movement are the finishing of the movement, shock protection, and round pushers.
Here’s mine, an officer’s chronograph with the 13-20CH movement from the early 1940s in a mid-size 33mm stainless steel case. The heavily patinaed silver dial complemented by those blued hands definitely goes a long way.