The Audemars Piguet Royal Oak Equation of Time is the first Royal Oak with a perpetual calendar, equation of times and an astronomical complication which usually go into Audemars Piguet’s other more elegant models. The watch uses the automatic caliber AP 2120/2808 movement with a forty hour power reserve and is so precise it only needs to be updated once once on March 1st 2100. The Audemars Piguet Royal Oak Equation of Time is available in either eighteen karat white or rose gold with an alligator strap.