What Does 'Oyster Perpetual' Mean?

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The words 'Oyster Perpetual' appear in the names of most Rolex wristwatch models. While most people only use the particular model name when referring to one of these timepieces, Daytona or Submariner for example, there is a reason the watchmaker includes these words as well. 

Photo of Rolex Oyster Case
Rolex Oyster Case (photo: Rolex)
The word 'Oyster' refers to the Oyster case that was developed and patented by Rolex in 1926. Shown in the photo above, this case creates a hermetic seal that gives all models that use this case a depth rating of 100 meters. The only model that does not use the Oyster case is the Cellini. For this reason, the 'Oyster Perpetual' is omitted when referring to Cellini models.

'Perpetual' refers to the Perpetual rotor of the movement housed inside the Oyster case. Patented by Rolex in 1931, the Perpetual rotor created a self-winding movement that was powered by a half-moon shaped oscillating weight that would rotate 360º with the natural movement of the wearer's wrist to generate power.

Photo of Rolex Perpetual Rotor
Rolex Perpetual Rotor (photo: Rolex)
These innovations created the first waterproof and automatic mechanical wristwatches on the market and while the patent on the Perpetual rotor expired in 1948, it still represents an important legacy that the watchmaker chooses to honor in the names of their current wristwatch models.

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Rolex Twinlock and Triplock Winding Crowns

.Tech.
The screw down winding crown was an important component of Rolex's first waterproof Oyster case design in 1927. Due to the fact that the winding crown interacts directly with the movement inside the case to perform essential functions of the watch, it is imperative that it creates a tight seal with the case to keep dust and water out. 

photo of Rolex Triplock Winding Crown
Rolex Triplock Winding Crown (photo: Rolex)
Rolex wristwatches are equipped with either a Twinlock or Triplock winding crown, depending on the model's depth rating. The Twinlock came first, introduced in 1953. Identifiable by two dots below the crown, the Twinlock winding crown has two sealed zones, one inside the tube and one inside the crown, to keep water out up to a depth of 100 meters.

The Triplock winding crown was introduced in 1970 and contains a third sealed zone inside the crown that increases water resistance to depths of up to 3,900 meters on the Rolex Deepsea model. The Submariner and Sea-Dweller models are also equipped with Triplock winding crowns.

While the winding crown may not be a deciding factor when purchasing a Rolex, it serves an important purpose in the hermetic seal of the Oyster case that the watchmaker has been perfecting for almost a century.

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Rolex Oyster Case

.Tech.
Rolex includes the words 'Oyster Perpetual' in most of their model names. The word 'Perpetual' refers to the perpetual rotor that powers the movement and, in this instance, the word 'Oyster' refers to the Oyster case that was invented by Rolex in 1926. 

Rolex Oyster Case (photo: Rolex)
The Oyster was the first waterproof wristwatch case that utilized Rolex's patented system of screwing the bezel, case back and winding crown into the middle case. It was tested by famed swimmer Mercedes Gleitze, who swam across the English Channel with a Rolex Oyster provided to her by Hans Wilsdorf in 1927.

All of the Rolex Oyster Perpetual models currently on the market are water resistant up to at least 100 meters due to the hermetic construction of the Oyster case. Today's Oyster case is made of a middle case that is stamped out of a solid block of metal (904l steel, 18 karat gold or platinum), a screw-down fluted case back and friction fitted crystal and bezel. Either a Twinlock or Triplock winding crown is also screwed into the Oyster case for watertight security.

All Oyster cases are made by Rolex in-house and undergo rigorous testing, including immersion underwater with high pressure to assure quality control. Although it may feel redundant to add the word 'Oyster' to every model name, the shape of the Oyster case is one of the easiest ways to identify a Rolex.

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