OMEGA Speedmaster Calibre 321

Omega's Speedmaster Calibre 321, reference 311.93.42.30.99.001, is a chronograph housed in a 42 mm platinum case. The case measures 13.39 mm thick with a lug-to-lug span of 47.6 mm. A black dial sits beneath a scratch-resistant sapphire crystal treated on both sides with anti-reflective coating. The manual-winding calibre 321 movement uses a column wheel mechanism and Breguet balance-spring, finished with 18K Sedna gold PVD coating, and runs for 55 hours on a full wind. Small seconds and a tachymeter scale round out the chronograph functions, and the caseback is transparent. A black leather strap with non-grained alligator underside closes on a platinum pin buckle. The case holds a rating of 50 metres.