This new ProSet caliber maintains the brand’s now-iconic perpetual calendar layout, with its double moonphase at 12 o’clock and a four-digit year display between 7 and 8 o’clock, though the power reserve display is gone, as this smaller version has a more standard 60-hour power reserve. But the internals here have been completely changed, with the architecture now entirely gear-based rather than depending on a traditional program disc, allowing for movement in both directions.
The caliber also uses what the brand calls extendable and retractable “fingers,” which allow for the perpetual calendar to change different indications, in conjunction with wheels that have multiple layers for information like the length of months or the leap year. Said layers activate the extendable fingers at the right time, like the end of each month or the change in the leap year cycle. These wheels and gears, due to their complexity, are manufactured through the LIGA process, allowing for more complicated shapes in the caliber. It’s all part of the IWC-manufactured 82665 caliber, modernized with a silicon hairspring and a nickel-phosphorus escapement.