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Explorer I Reference 214270
"MK1 & MK2"
Rolex's most controversial Explorer decision: growing the case from 36mm to 39mm. The watchmaking world was divided. Purists lamented the departure from the canonical size; others welcomed the more contemporary wrist presence. The 214270 MK1 (2010–2016) had thinner Arabic numerals that some felt less bold than tradition demanded. The MK2 (2016–2021) addressed this with updated numeral proportions and Chromalight throughout. Cal. 3132 introduced the Parachrom hairspring — 10× more shock-resistant than standard steel, unaffected by magnetic fields.
Notable: The 39mm size divided the collector community. Both MK1 and MK2 are now highly sought, with MK1 attracting premium as the "controversial original".
Technical Specification
| Reference | 214270 |
| Production years | 2010–2021 |
| Case diameter | 39 mm |
| Case material | 904L Oystersteel |
| Movement | Cal. 3132 |
| Jewels | 31 |
| Frequency | 28,800 bph |
| Power reserve | 48h |
| Crystal | Sapphire, flat |
| Water resistance | 100m |
| Bracelet | Oyster with hidden Oysterclasp & Easylink |
| Lume | Chromalight (blue, long-lasting) |
| Dial colour | Black lacquer |
| Numerals | 3–6–9 Arabic, larger scale, applied white gold |
| Hands | Mercedes hour hand, slightly longer, Chromalight fill |
| Crown | Twinlock Oyster crown |
| Serial range | Random serial (from 2010) |
Variants & Production Marks
MK1 (2010-16): 39mm, thinner Arabic numerals, Cal. 3132
MK2 (2016-21): 39mm, bolder numerals, updated Chromalight lume