Housed in a case of 44mm, the Royal Oak Tourbillon Chronograph is one of the largest non-Offshore Royal Oak models available. It is powered by the hand-wound caliber 2889 movement, which pairs a tourbillon with a column wheel chronograph - an signature AP combination.Reference 25977ST.OO.1205ST.02 has a stainless steel case and a matching bracelet.The dial is black.