With Rolex fitted presentation box.
Rolex introduced the Explorer in January 1953, for explorers wherein the dial was very visible, the case extra strong and a special oil could be used on occasion if required to render the watch able to withstand temperature fluctuation from frigid to hot. An Explorer is generally defined by its black dial, a large luminous dagger marker at 12 o'clock and luminous Arabic numerals at the other quarters. The Explorer model was present when Edmund Hilary and Tenzing Norgay stood as the firsts to reach the summit of Mount Everest on May 29, 1953, though only Norgay was actually wearing a Rolex on his wrist.
The first Explorer produced was the reference 6350, and about a year later was replaced by the reference 6150. The 6150 distinguished itself by being 2 mm. larger than its predecessor and was only available as a Precision model. In 1959, the 6150 was replaced by the 6610, which featured a flatter back - due to the use of the newer 1030 calibre movement, and a dial further signed Chronometer.