Seamaster Automatic CK2657 — CK2657, Caliber 344

Later production with the 17-jewelJewelA natural or synthetic stone used as a bearing or endstone for a movement pivot. bumper caliberCaliberThe designation of a watch movement, identifying its design or movement family. 344 (about 42 hours of power reserve); the cited example's movementMovementThe working mechanism inside a watch or clock. dates to 1952.