Launched in 2015, the IW5035 family introduces the Annual Calendar complication to the Portugieser (aka Portuguese) collection. The month, date and day are displayed through three arched windows at 12 o'clock. The present version, reference IW503504, has a red gold case and a silver dial. It is powered by the IWC-manufactured 52850 calibre.
Located at “12 o’clock” on the dial, IWC’s annual calendar shows the month, date and day in three separate windows. The mechanism automatically takes into account the differing lengths of individual months. Unlike a perpetual calendar, however, the annual calendar is unable to make allowance for the leap days in February or the leap years. Once a year, then, at the end of February, it requires manual correction. In the case of IWC’s annual calendar, the correction is made simply, via the crown.