Omega's first professional diver, born in the 1957 trilogy beside the Speedmaster: six references from the broad-arrow CK2913 to the thick-bezel 165.024, its date-equipped sibling, and the Royal Navy issue that ended the line in uniform. A watch that says 300 and promised 200, documented either way.
| REFERENCE | PRODUCED | CALIBER | CASE | RATED |
|---|---|---|---|---|
| Omega CK2913KEY | c. 1957–1961 | 501 (500 in US) | 39 mm | 200 m |
| Omega CK14755 | c. 1960–1962 | 552 | 39 mm | 200 m |
| Omega 165.014 | c. 1962–1964 | 552 | 39 mm | 200 m |
| Omega 165.024KEY | c. 1963–1970 | 552 | 42 mm | 200 m |
| Omega 166.024 | c. 1966–1970 | 565 | 42 mm | 200 m |
| Omega 165.024 "Royal Navy issue"KEY | 1967–1971 | 552 | 42 mm | 200 m |
"c." marks a production window documented as approximate — including by Seiko's own archive.