Rolex 710 17J (Precision)

History: The Rolex 710 is also known as the Gruen 827 and was in fact made by Aegler (as were all Rolex movements prior to 2004). It is one of the many movements derived from the Hunter 10 1/2. This is the 17 jewel version. Main spring: 1,50 X 8 - 0,09 - 270. Manual wind, screw balance or super balance.

The 710 is closely related to the Aegler 700. The primary difference is the position of the second hand. The 700 is "sub second", whereas the 710 is "center second".

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