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. 

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.

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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