OMEGA Speedmaster Calibre 321

The Omega Speedmaster Calibre 321, reference 311.50.39.30.01.001, has a 38.6 mm case in white gold. The case measures 13.92 mm thick with a lug-to-lug of 48 mm, sized for a man's wrist. Inside is the manual-winding calibre 321, a column-wheel chronograph movement with a Breguet balance-spring, offering 55 hours of power reserve. A sapphire crystal with anti-reflective treatment on both sides covers the black dial. This chronograph carries a tachymeter scale and small seconds, and the caseback is transparent to show the movement. The white gold bracelet closes with a foldover clasp fitted with a comfort setting. The clasp itself is rated to hold the case at a water resistance of 60 metres.