Like all Rolex watches, the Oyster Perpetual GMT-Master II is covered by the Superlative Chronometer certification redefined by Rolex in 2015. This designation testifies that every watch leaving the brand’s workshops has successfully undergone a series of tests conducted by Rolex in its own laboratories according to its own criteria, following the official certification of the movements by the Swiss Official Chronometer Testing Institute (COSC).To power the 1908, Rolex’s watchmaking engineers have developed a completely new self-winding movement, calibre 7140, that allows the time to be displayed via two central hands and a small seconds hand at 6 o’clock. A number of patents have been filed for this movement, which has been entirely developed and manufactured in-house. Its cutting-edge design incorporates some major innovations from the Manufacture to guarantee exceptional performance, including the Syloxi hairspring in silicon, Chronergy escapement in a nickel-phosphorus alloy – both of which are resistant to strong magnetic fields – and Paraflex shock absorbers, which protect the oscillator and escape wheel from any shocks to the watch.