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 25977BA.OO.D088CR.01 has a yellow gold case and an integrated alligator strap. The dial is silver.