The IWC Portugieser Perpetual Calendar 5023 made its debut in 2010, combining IWC's self-winding movement with Kurt Klaus' clever perpetual calendar module. This module was first seen in the 1985 Da Vinci and was modified to fit the larger 7-day movement. The watch boasts a 44.2mm case with sapphire glass on both sides. One unique feature is the 'Single Moon' display, which allows the wearer to easily read the moonphase in their hemisphere. This particular model, the IW5023-06, features a red gold case and a silver dial, and was released in 2011.