I bought this AIRAIN dive watch, but am unable to find any photos or other information online to identify it. It has two 'brevet' (patent) numbers stamped inside the caseback, so for want of a better name I'm going to call it the Brevet.
It's clearly a close relative of the AIRAIN Sous-marine, but the Brevet lacks a rotating bezel and the word Sous-marine, and has two things the Sous-marine doesn't: a non-cyclops date magnifier set into the crystal, and a Parmentier screw-down crown (although looking at that Sous-marine crown, maybe it is a Parmentier). Otherwise the watches have identical dials, numerals & indices.
The Brevet has an automatic ETA 2472 caliber, 30 jewels.
Diameter is 34mm, full height 41.4mm, strap width 18mm.
Thought to be from the early 60s.
(The brevets are as follows: Brevet 238872 from 1945 for the inner case tension ring for compressible watch cases, and Brevet 357352 from 1959 for the waterproof winding crown design).
If anyone has any information about this watch, I'd be very interested!

 

What an amazing looking dial! I love how whimsical and interesting it looks without the bezel. Thanks for sharing - have you found any new information on the “Brevet?”