The Sky-Dweller is also an annual calendar, the function based on a mechanism called Saros, after the Greek term for the 18-year cycle 
between the sun, earth, and moon, which is responsible for both lunar and solar eclipses. How the function works is cleverly simple, with only two gear ratios and four gear wheels added to the traditional Rolex date system to provide an accurate annual calendar that you would need to reset only once per year, at the end of February. At the end of each 30-day month, an extra impulse is given to the date-change mechanism, which causes the date to jump two days within a few milliseconds at midnight. The month is then indicated through small rectangular windows on top of the hours, with January represented by 1 o'clock, February by 2 o'clock and so forth.
The automatic calibre 9001 is the most complex movement Rolex has produced so far, with seven patents on the movement alone. It has all the makings of a typical Rolex movement – the Parachrom hairspring and Paraflex shock absorbers, a large balance wheel and COSC certification – and is particularly impressive because of its 72-hour power reserve, even with the energy needs of the Saros annual calendar and Ring Command system.
While purists are saying that the Sky-Dweller is a totally unorthodox release from the brand, with its combination of complications, the watch definitely indicates Rolex's desire to create challenging and thought-provoking pieces. Some watch aficionados are even hedging on this particular watch becoming a cult classic just like the Ref 8171 from the 1950s, which, with a triple-calendar and moonphase, is still one of the brand's most complicated pieces.
Available in 18k white gold with bracelet, 18k yellow gold with bracelet and Rolex’s Everose gold on a leather strap, the 42mm Rolex Sky-Dweller is expected to make a smooth landing in Hong Kong soon.
