A British-founded Swiss watch designer and manufacturer based in Geneva, Switzerland, Rolex was founded in 1905 as Wilsdorf and Davis by Hans Wilsdorf and Alfred Davis in London. Each Rolex comes with a unique serial number, which can help indicate its approximate production period. Serial numbers were first introduced in 1926 and were issued sequentially, until 1954, when Rolex restarted from #999,999 to #0. In 1987, there was an addition of one letter to a 6-digit serial number and from 2010 right down to the present date, Rolex has introduced random serial numbers.