Glossary
A plain-language definition of Oyster case — what it is and why it matters on a Rolex.
In 1926 Rolex hermetically sealed a wristwatch by screwing the bezel, caseback, and crown down against the middle case — like an oyster shell, hence the name. A year later Mercedes Gleitze swam the English Channel wearing one, and it emerged in perfect working order, proving the concept.
Nearly a century on, every Submariner, Datejust, and Daytona is an Oyster: the same screw-down architecture, refined with modern crowns (Twinlock, Triplock) and materials. Pair the Oyster case with the self-winding Perpetual rotor and you have the Oyster Perpetual, the core of the whole catalogue.
Related terms
Oyster case FAQ
It is Rolex's waterproof case, introduced in 1926 as the first commercially successful waterproof wristwatch. It seals with a screw-down caseback, bezel, and crown.
Because, like an oyster shell, it is hermetically sealed — the bezel, caseback, and crown screw down tightly against the case to keep water and dust out.