IW5021-21

The IWC Portugieser Perpetual Calendar 5021 was introduced in 2003, pairing IWC's self-winding 7-day movement with Kurt Klaus' ingenious perpetual calendar module. The latter was first seen in the 1985 Da Vinci and adapted to fit the larger dimensions of the 7-day movement. It featured a case of 44.2mm with sapphire glasses both front and back. One of its signature elements was the 'Double Moon' moonphase display, allowing its owner to read the moonphase in both the southern and northern hemisphere. The 5021 was accompanied by the slightly smaller 5022 ('Single Moon') in 2006. This reference, the IW5021-21, has a white gold case and a blue dial. It was introduced in 2010.