Geneva-based Tudor Watches is a sub-brand of Rolex, originally registered in 1926 by Hans Wilsdorf, best known as the founder of Rolex SA. Rolex Watches Today, Tudor and Rolex are part of the same company. Both are owned by the Hans Wilsdorf Foundation. In 1954, Tudor's Oyster Prince Submariner was introduced. This tool watch has continued to evolve to meet the needs of divers over the years. In the decades between the 1960s and 1980s, several navies issued Tudor submarines to divers. including the elite SEALs of the United States Navy and the French Marine Nationale. From 1969 to 1999, over 20 different Tudor Submariner references were built. In 2015, Tudor introduced its in-house caliber as the The first, the MT5621, is a self-winding caliber with a bi-directional rotor system.