For a mountainous country crawling with precision engineers, Switzerland is rather poorly represented in the derailleur universe. I know of four Swiss companies that dabbled in derailleurs:

• In the 1940s and 1950s Versol produced a variety of rod operated single pulley and pull chain single and double pulley designs.
• In the 1950s SIL produced a couple of tidy but unexciting pull-chain derailleurs.
• In the 1980s ICS customised, at unbelievable expense, the Campagnolo Super Record, in a vain attempt to improve its change.
• From the 1980s to the 1990s EDCO rebranded first Simplex and then Sachs derailleurs, as it needed to complete a groupset in order to sell its headsets, bottom brackets (?), hubs and chainsets.