The world renowned Oyster pressure-proof case was invented and patented by Rolex in 1926. Today, every handcrafted Rolex Oyster is rigorously tested for its ability to provide pressure-proof performance to depths ranging from 330ft/100m to 4000ft/1220m, depending on the Rolex Oyster model. When your Rolex Oyster case is serviced, it is once again tested in a special vacuum tank developed and patented by Rolex, which verifies the protective features of the case.