Seamaster PloProf 166.077 — 166.077, Prototype · 166.077, R&D Prototype with Caliber 1001

Development-department test piece with a “000” movementMovementThe working mechanism inside a watch or clock. number (00'067'644) and a chronometerChronometerA watch or movement certified for timekeeping precision under a defined testing standard. The applicable certification depends on its maker and period; it is not the same as a chronograph. caliberCaliberThe designation of a watch movement, identifying its design or movement family. 1001 developed to resist water-temperature changes, per the archive.