Introduced in 2005, the Royal Oak 15300 was the first 'simple' Royal Oak to feature an in-house movement: caliber 3120. Reference 15300ST.OO.1220ST.02 has a stainless steel case and matching bracelet. The dial is blue.
The in-house caliber 3120 has a total of 280 parts. The rotor, in 22ct gold, is mounted on ceramic ball bearings.