Mechanism: The 3135 is a continuation of the 3035 series. Rolex launched it in 1977 and was profoundly different from its predecessors. As the company’s first high-beat movement, it increased the balance speed from 19,800 BPH to 28,800 BPH. This higher frequency has since become the standard across all of Rolex’s range. It also allowed the caliber to provide more accurate timekeeping and better withstand outside influences, such as shock. Like most Rolex mechanisms ending with a "5", this unit has a date function. All modern Rolex date-equipped mechanisms have a 'Quickset' feature as well.

The popular caliber 3135 measures 28.50 mm in diameter and 6.00 mm in height. The Submariner uses this caliber. This makes it quite large when compared with other Rolex movements. The larger size of the movement means that it is more robust and has the ability to incorporate more parts and components. This allows the watch that utilizes it to perform more reliably and durably. It also offers a frequency of 28.800 vph.

Family Notes: The Datejust emerged in 1945, introducing the watch world to the innovative automatically changing date window. This feature made watch history and has since made the Datejust one of Rolex's most successful models. The ladies model that was introduced a few decades later has enjoyed a large amount of success as well, thanks to its functional yet luxurious design. The Rolex Datejust is the modern archetype of the classic watch, thanks to aesthetics and functions that transcend changes in fashion. Aesthetically, the Datejust has spanned eras, while retaining the enduring codes that make it, notably in its traditional versions, one of the most recognised and recognisable of watches.

Originally named the Jubilee Datejust, Rolex Datejust history began in 1945 when Rolex released the model for the company's 40th Anniversary. It was a direct descendant of the Bubbleback and included a date function, which was placed at the 3 o’clock position on the face. The Datejust had a coin-edge bezel, which later became the flutted bezel. It was the first watch to show the date automatically and also the first to change the displayed date at exactly midnight. The Datejust was innovative, unique, and different than any other watch offered at that time.

The history of Rolex Datejust begins with the first Datejust, the Jubilee Datejust Model 4467, which was only available in 18k gold and had a small bubbleback winder with a deeply domed back. In the 1950's, the Oysterdate joined the Datejust family, coming in two sizes. Although the Datejust originally consisted of three case parts, it was quickly updated to just two. Another major update was the addition of the Cyclops lens in 1954. Today this lens is standard to Rolex watches and even part of the brand’s signature. Before 1954, however, no one had used a magnifying bubble on the lens right above the date. Then, in 1957, a new, lighter, slimmer movement, the caliber 1065, allowed for a flattened case back in place of the old domed one. That same year, the Datejust became available in Steelium (stainless steel) in addition to the original gold. Other changes over the years included a flat dial (rather than curved) and the Rapid Date Change (aka quickset) feature.

The fact that Rolex Datejusts are still purchased and worn today is a testament to their enduring respectability and timelessness. To understand the Rolex Datejust history, pictures can be worth a thousand words. Seeing pictures of multiple presidents and other powerful people wearing the Rolex Datejust shows the importance and significance of this watch.