Panerai
radiomir black seal limited edition - Calibre OP XI Visible

The Panerai Radiomir Black Seal is a limited edition Decima MAS tribute watch from 2004, inspired by the timepieces worn by the combat divers of the Italian Decima MAS unit led by Prince Valerio Borghese. It features a 45mm polished 316L stainless steel cushion-shaped case, a screw-down crown engraved with the Panerai logo, and a black sandwich dial with luminous Luminova inserts. The transparent caseback allows a full view of the mechanical movement in action.

The watch is powered by the Panerai Caliber OP XI, a beautifully finished 17-jewel movement based on the ETA (formerly Unitas) 6497-2, the same structure once used in pre-war Rolex-powered Panerai watches. This modernized version features a gold-colored monometallic “Glucydur” balance wheel made of copper alloyed with 3% beryllium and 0.5% nickel. This composition makes it highly resistant to corrosion, magnetic fields, and temperature changes — thanks to Glucydur's exceptional elasticity and hardness. The regulating escapement, allowing fine-tuned factory adjustment, is produced by Nivarox-FAR, a prestigious manufacturer located in the Swiss valley of Saint-Imier. An Incabloc shock protection system completes the technical upgrades, all visible through the sapphire crystal caseback.

To conclude the technical overview of this historical collector’s watch, it offers a power reserve of approximately 56 hours after full winding and operates at 21,600 vibrations per hour. It is also officially certified as a chronometer by the COSC in Geneva. This piece is offered as a complete collector’s Full Set with its original box and papers.

Produced in very limited numbers and crafted with special care, this edition celebrates Panerai’s heritage as a military dive watch manufacturer with a storied past. Nicknamed "Alexandria" by collectors, the edition pays tribute to the Decima Flottiglia MAS (for Mezzi d’ASsalto), particularly to the torpedo riders (Maiali) who, on December 18–19, 1941, successfully attacked and sank the British battleships HMS Valiant and HMS Queen Elizabeth during an amphibious operation in Alexandria's harbor.

To learn more about timepieces that made history and the watchmakers behind them, visit our "Watch Stories" page, where you’ll find a library of historical articles organized by brand, model, and celebrity-worn watches.