Ref. 329.23.44.51.06.001 - This Speedmaster Racing Master Chronometer model with a grey leather strap features a 44.25 mm stainless steel case with an 18K Sedna™ gold bezel. The silicon nitride bezel ring is inlaid with the famous tachymeter scale in OMEGA Ceragold™. - The matte grey dial features a striking racing-style minute track, from which the watch derives its name. It also has two subdials with rhodium-plated applied rings and a date window at 6 o'clock, color-matched to the dial. The hour and minute hands and arrowhead hour markers are crafted from 18K Sedna™ gold with white Super-LumiNova. - The watch is powered by OMEGA's Co-Axial Master Chronometer 9900, which has been certified by METAS to the highest industry standard.