Omega, Speedmaster Moonphase Co-Axial Master Chronometer, reference 304.33.44.52.01.001. 44.25 mm stainless steel case, midnight blue dial with moon phase, tachymeter bezel. Co-Axial Master Chronometer automatic movement with chronograph and moon phase. In very good condition. The Speedmaster Moonphase is the most sophisticated complication in the range. Original box and certificate of authenticity.