The watches that IWC Schaffhausen has created in celebration of its 150th anniversary have in common a blue or white lacquered dial. Five of these limited editions have been added to the brand's oldest collection, the Portugieser. The mechanical highlight is this constant-force tourbillon, the first from IWC. Equipped with a new, manual-wind manufacture movement, its moonphase display is so precise it will need adjusting by just one day after 577.5 years. The patented constant-force mechanism transfers a perfectly regular flow of energy to the escapement throughout the 96 hours of power reserve.