Rolex GMT Master II 116710BLNR Black Dial u0026amp; Black and Blue Bezel Stainless SteelnModel featuresnThe GMT-Master II is equipped with calibre 3186, a self-winding mechanical movement entirely developed and manufactured by Rolex. In addition to the conventional hour, minute and seconds hands, it features a 24-hour hand to display a second time zone. Like all Rolex Perpetual movements, the 3186 is a certified Swiss chronometer, a designation reserved for high-precision watches that have successfully passed the Swiss Official Chronometer Testing Institute (COSC) tests. The 3186 is equipped with a Parachrom hairspring, offering greater resistance to shocks and to temperature variations. Its architecture, in common with all Oyster watch movements, makes it singularly reliable.