UG you think? Wrong: Omega. https://www.lacasadellorologio.it/e...torno-in-corona-calibro-base-omega-333-omega/
Really intruiging to see how a lot of high end chrono's in the 1930's looked very similar
IMHO the pinnacle of 1930's UG: https://www.sothebys.com/en/buy/auc...ograph-wristwatch?locale=en&cmp=agg7000200568
Agreed. On both the protrusion on the case which connect with the lugs has ridges in it. The one I posted (as well as the one with serial 583.584 - see https://omegaforums.net/threads/serials-2-consecutive-numbers.147786/page-3#post-2265287) don’t have that. As always: nothing UG is straight forward