The rugged Oyster case was great to match demands in certain specific professional fields. We all know models like the Submariner (intended for divers), GMT (intended for pilots), Daytona (intended for racing) but it actually all started in the early ’50s with the Turn-O-graph. The name, basically, meant that the bezel could turn so it could be used for measurements. Its very first model, the reference 6202, looked design-wise like what would later become the Submariner. A very rare and sought-after reference.