The Rolex Oyster Perpetual Date Sea-Dweller is a line of diver's watches manufactured by Rolex, with an underwater diving depth rating of 1,220 meters (4 000 ft) and up to 3,900 metres (12,800 ft) for the Sea-Dweller Deepsea model. Launched in 1967 with a diving depth of 610 metres (2 000 ft), the Sea-Dweller features a gas escape valve, developed by the brand specifically for watches, which allows the helium trapped in the watch while decompressing to be released at a given pressure during decompression, while preserving the watch case's water resistance. Today's Sea-Dweller models are available in steel or steel and yellow gold, and have a 43 mm case. The Deepsea model comes in a 44 mm case in steel and is equipped with the brand's patented Ringlock system, which was designed to provide a higher degree of pressure resistance.