OMEGA Speedmaster Calibre 321

Omega's Speedmaster Calibre 321, reference 311.30.40.30.01.001, is a chronograph with a 39.7 mm steel case. The case measures 13.7 mm thick with a lug-to-lug span of 48 mm. A sapphire crystal with anti-reflective treatment covers the black dial, and the display back shows the manual-winding calibre 321 inside, a column-wheel chronograph movement with a Breguet balance-spring and 55 hours of power reserve. The dial carries small seconds and a tachymeter scale for the chronograph function. A steel bracelet with a folding clasp completes the watch. Omega rates the case to 50 metres of water resistance.