Rolex 4130

History: The Cosmograph Daytona is equipped with calibre 4130, a self-winding mechanical chronograph movement entirely developed and manufactured by Rolex. Its architecture incorporates far fewer components than a standard chronograph, thereby enhancing the movement’s reliability. Like all Rolex Perpetual movements, the 4130 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 chronograph movement features a Parachrom hairspring, offering greater resistance to shocks and to temperature variations.

By design, the 4130’s vertically coupled approach enables absolutely precise starts and stops of the chronograph seconds hand. When started, stopped, or reset, no unwanted jitters are seen on any of the watch’s hands. The vertical clutch also allows the chronograph to run continuously for extended periods, with no impact on timekeeping accuracy. Understanding Rolex’s longstanding, noble pursuit of maximum timekeeping accuracy, their decision to use a vertical clutch makes sense.

Rolex released the caliber 4130 in 2000. It is completely designed and manufactured by Rolex themselves. It supplants the Zenith El Primero as the movement for the Daytona series of watches. Presumably, the move towards the 4130 was due to the race to become 100% in-house – and possibly issues with servicing the Zenith-made 4030 caliber (for example: less parts).

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