Introduced in the mid-1980s, the Rolex Explorer II ref. 16550 was a short-lived but important transitional reference between the original ref. 1655 and the long-running ref. 16570. Its most significant mechanical development was the automatic calibre 3085, which introduced an independently adjustable conventional hour hand. This transformed the fixed 24-hour indication of the original Explorer II into a true second-time-zone display. The 16550 also introduced sapphire crystal, a redesigned 24-hour bezel and, for the first time in the Explorer II family, the option of a white “Polar” dial.

The present watch is a later example with a non-rail white dial featuring black surrounds to the luminous hour markers. This dial configuration may represent a later service replacement, particularly as the watch retains steel hands rather than the black hands associated with the subsequent ref. 16570; without supporting Rolex documentation, however, we cannot establish when the dial was fitted. Particularly attractive is the tritium luminous material, which has developed a rich vanilla tone across the dial and hands. Together with the drilled-lug case and fixed steel 24-hour bezel, these details capture the transitional nature that makes the ref. 16550 such an interesting chapter in the Explorer II's evolution.