What changed in the 3861 era
The current Moonwatch keeps the familiar 42 mm case, step dial and ‘dot‑over‑90’ bezel detail, but inside beats the **Co‑Axial Master Chronometer calibre 3861**. This brings **anti‑magnetic** architecture tested to **15,000 gauss**, whole‑watch accuracy certification and a revised bracelet with five smaller links per row.
Hesalite or sapphire?
**Hesalite** echoes the watches worn in space; it’s warm and can be polished at home if scratched. Its caseback carries an embossed Seahorse medallion. **Sapphire** offers more scratch resistance, a display back and applied logo. Both versions are water‑resistant to 50 m and deliver the same movement performance.
How it wears
Despite its legend status, the Moonwatch is still a practical daily chronograph. The case profile slips under cuffs better than you think, and the revised bracelet improves comfort. Legibility is excellent, and the hand‑wound ritual is part of the charm.
At‑a‑glance
- Case: 42 mm steel, 50 m WR; anodised aluminium bezel
• Movement: **calibre 3861**, Master Chronometer (METAS)
• Variants: hesalite (solid back) or sapphire (display back)
• Why buy: authentic design, modern performance, iconic status
Sources
Omega — Grand Seiko-style dedicated page for SLGH005 is used as a reference for official spec structure (Omega site can be JS-heavy).
GQ — 2021 Moonwatch update (3861, step dial, bracelet): https://www.gq.com/story/omega-speedmaster-new-2021
WIRED — White dial 2024 & movement/context: https://www.wired.com/story/white-omega-speedmaster-moonwatch-2024
Retailer tech listings (ref 310.30.42.50.01.001, hesalite): https://martinjewelers.com/products/omega-5
