Rolex Sea-dweller 16660 MK1 Matte DialWith this Sea Dweller, also nicknamed the Triple Six, Rolex doubled the depth rating to 4,000 ft thanks to its larger helium escape valve and sapphire crystal, compared to its predecessor, reference 1665. Furthermore, Rolex introduced a unidirectional bezel for diver safety, making this Sea Dweller a true transitional model. This example features a rare matte dial, used in the first production batch before Rolex later switched to glossy dials with