Basing on the calibre Rolex 3135, it features an additional GMT indication (dual time zone). It is used in the GMT-Master II Ref. 16710 and Explorer II Ref. 16570. Cal. 3185 was updated with Parachrom springs and a spring-loaded date mechanism around 2005 to become Cal. 3186. The larger Cal. 3187 was used in the Explorer II, Ref. 216570 starting in 2011.
- Date change via dual time zone