The new Audemars Piguet Royal Oak ref. 15400ST.OO.1220ST.04 is the latest 41 mm Royal Oak released earlier this year with a fantastic grey ruthenium toned dial. This reference is a clear result of the continuous evolution of the Royal Oak and the manufacture's constant forward thinking. Since its launch in 1972, the Royal Oak has gone through several design modifications and the ref. 15400 with this new grey dial is simply perfect. With this new dial, the Royal Oak ref. 15400ST is now available in four different dial variants that include blue, silvered white, black and this new one.