Omega, Cal. 30.10 powered, Bumper Automatic, two-tone silver dial with roman indexes, rare engraved back case, circa 1940s.
It is one of the rare half-rotor bumper automatic models before the full-rotor automatic models were born, and its distinctive mechanical sound is unique to bumper type watches. The unique water-resistant case with metal O-rings on the snap-back cover and the silver two-tone dial with luminous Roman design are a gem of the era and great taste. This is a rare engraved back model for a ring snap back waterproof case, and the 11 o'clock lug is engraved with the Portuguese name.