A ref. 3940P from the Third Series with a silver moon and incredible case condition, preserved in its full set. The first Patek Philippe Perpetual Calendar made at scale, the 3940 is serious complication made simple at 36mm. Its revolutionary micro-rotor calibre 240Q is a masterpiece of micro-engineering, just 3.75mm thin. Of all 3940 production, platinum is the rarest metal. Only platinum examples preserved the solid caseback-only tradition through production.