Many people consider that the perfect fake Rolex Sea-Dweller looks similar to Submariner. The appearance of them are really similar and the biggest difference between them must be the helium escape valve set on the side of case of the Sea-Dweller.
All the professional diving watches will be equipped with the helium escape valve. It is set to prevent the danger when floating from the deep sea. It allows the helium to escape from the case, keeping the balance of the pressure outside of the case and inside. The black dial copy Rolex ref.1665 was the first generation which was manufactured from 1971. It was water resistant to the depth of 610 meters.
While the imitation watch ref.16660 with Oystersteel case released later achieved to a depth of 1,220 meters. It adopted the robust sapphire crystal.
