sentences:  Several semi-custom production runs of Sea-Dweller Submariner 2000 and 4000 models were produced with and without helium escape valves and differing watch dial patterns for the Comex S.A. company.These variants sometimes also had differing Rolex reference numbers.Some of these non-standard Sea-Dweller watches had the Comex S.A. logo depicted on the watch dial, which led to an unofficial "COMEX watches" designation by collectors.