The Audemars Piguet Royal Oak Openworked Tourbillon 26511 was produced in a highly limited series of 40 watches to commemorate the 40th anniversary of the Royal Oak. This stunning, 41mm watch features a gorgeous movement which deserves to be on display on this skeletonized watch. This platinum Royal Oak is in like-new condition having only been worn a few times and comes with an extract from AP.