Rolex 3136

History: The 3136 movement was designed to have the feature set of the 3135 but is able to take advantage of the larger space allowed by the new Datejust II 41mm case. The calibre 3136 is two and a half millimetres larger than the 3135 and it has been consolidated into the e.g. 41 mm sized Rolex Datejust. While other manufacturers just call it a day by repackaging the same calibre into a larger watch case, the brand has opted instead to launch an entirely new movement. Its dimensions have been fine tuned to meet the current demands of everyday wear that’s placed on Rolex watches that have surpassed the 40 millimetre mark.

Calibre 3136 is a self-winding mechanical movement entirely developed and manufactured by Rolex. Like all Rolex Perpetual movements, the 3136 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 3136 features a Parachrom hairspring and high performance Paraflex shock absorbers developed by Rolex, offering greater resistance to shocks and to extreme conditions. Its architecture, in common with all Oyster watch movements, makes it singularly reliable.

Manufacturer: Rolex SA (/ˈroʊlɛks/) is a Swiss luxury watchmaker. The company and its subsidiary Montres Tudor SA design, manufacture, distribute and service wristwatches sold under the Rolex and Tudor brands. Founded by Hans Wilsdorf and Alfred Davis in London, England in 1905 as Wilsdorf and Davis, Rolex moved its base of operations to Geneva, Switzerland in 1919. Forbes ranked Rolex 64th on its 2016 list of the world's most powerful global brands.[Rolex is the largest single high end watch brand. The company is owned by the Hans Wilsdorf Foundation, a private family trust.

Alfred Davis and his brother-in-law Hans Wilsdorf founded Wilsdorf and Davis, the company that would eventually become Rolex SA, in London, England in 1905. Wilsdorf and Davis' main commercial activity at the time involved importing Hermann Aegler's Swiss movements to England and placing them in high-quality watch cases made by Dennison and others. These early wristwatches were sold to jewellers, who then put their own names on the dial. The earliest watches from Wilsdorf and Davis were usually hallmarked "W&D" inside the caseback.

From Wikipedia