Rolex Explorer II Steel — Black Dial 24-Hour Bezel | Ref. 226570

Introduced in its current 42mm form for 2021, the Explorer II reference 226570 represents Rolex's most consequential update to this iconic professional instrument in over a decade. Originally conceived in 1971 for cave explorers navigating environments where day and night distinction is impossible, the Explorer II retains its defining fixed bezel engraved with 24-hour graduations — here rendered in black-tipped numerals against a matte ring — and its large orange GMT hand that sweeps a full day on a single revolution, enabling independent tracking of a second time zone or AM/PM disambiguation underground.

At the heart of the 226570 beats the Calibre 3285, Rolex's generation-current movement architecture for GMT complications, sharing its fundamental engineering DNA with the 3235 used in the Submariner and Datejust. The 3285 incorporates the Chronergy escapement — a patented geometry delivering 15 percent greater energy efficiency — alongside a Parachrom hairspring in a blue paramagnetic alloy, providing stability in the presence of magnetic fields up to 15 times stronger than those encountered in daily life. A power reserve of approximately 70 hours exceeds COSC chronometer tolerances by a significant margin.

The black dial features hour markers charged with blue Chromalight, Rolex's proprietary long-duration luminescent compound that emits a distinctive blue glow lasting twice as long as conventional phosphorescent materials. The Oyster bracelet in 904L Oystersteel, paired with the folding Oysterlock safety clasp and Easylink 5mm comfort extension, provides the same secure, tool-grade wearability that made the Explorer II the instrument of choice for polar expeditions and underground surveys. Water resistance is rated to 100 metres.