The Audemars Piguet Royal Oak Double Balance Wheel Openworked ref. 15407 is without a doubt one of the top watch grails to own when it comes to AP and in general. With a case measuring 41 mm and 5.51 mm in thickness, its movement tackles the stabilizing issues by fixing a second balance wheel and balance-spring assembly on the same axis. The new patented geometry involves a very complex manufacturing procedure, but the payoff is huge by having greatly improved precision and stability. Fitted with a slate grey open-worked dial with white gold applied hour-markers and Royal Oak hands with luminescent coating, this watch is truly a stunner.