The Ingenieur Perpetual Calendar Digital Date-Month is the flagship of the Ingenieur family. The design is inspired by the very first Ingenieur models and features a simple round case and polished bezel. The perpetual calendar with large digital date and month displays, which can be easily set using the crown, recognizes the different lengths of the months and takes into account the leap day every 4 years. The IWC-manufactured 89801-calibre movement also features a chronograph function. This timepiece has a 45-millimetre case made from 18-carat red gold, a silver-plated dial, black hands and a black alligator leather strap, and is limited to 100 watches.