Rolex 1601

History: The 1600 series is a family of very traditional manual wind movement reserved exclusively for Cellini models. The winding pinion, clutch wheel, and the stem are interchangeable. The 1601 is the second iteration of the group. It measures 20.8 mm in diameter and 2.55 millimeters thick. The 1601 uses a regulator, whereas the later 1602 is freesprung.

Frequently, when someone begins to get interested in Rolex Cellini watches they often want to know what is inside of one. “Is it the same movement as a Submariner or a Datejust?” “Is it technically advanced?” etc. Sorry, but no it is not. Cellinis have their own movements which are totally different from other Rolexes. First off, they are manually wound watches, not automatics. Second they are for "dress" watches so they have a different form-factor. These movements are hence much thinner than other Rolex mechanical mechanisms. That being said, they are still well made quality movements.

The 1600 was first produced in 1964 and the 1602 introduced in 1993. This places the release date of the 1601 likely in the late 1970s.

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