Rolex Oyster Perpetual Sky-Dweller.The watch features an annual calendar and a second time zone function. The former has a regular date display, while the month is displayed through apertures by the hour markers. The latter is indicated through an off-centre 24h disc at 6 o'clock. The well-known fluted bezel functions as sort of a gear box with three positions, enabling the user to set the date, local time and second time zone through one single position on the crown.