OMEGA Speedmaster '57 Co-Axial Master Chronometer Chronograph 40.5mm 332.10.41.51.10.001MOVEMENT Calibre: OMEGA 9906 Manual winding chronograph with column wheel and CoAxial escapement Certified Master Chronometer, approved by METAS, resistant to magnetic fields reaching 15,000 gauss. Silicon balance spring, 2 barrels mounted in series, time zone function. Central hour, minute and chronograph seconds hands, date function, small seconds counter, 12 hour and 60 minute counter. Rhodium plated finish with Geneva waves in arabesque Power