1940s ROLEX OYSTER Ref.4242 ”Monoblocco” Cal.NA Very Rare 35mm Bubble back

Early 1940s Rolex Bubble Back Ref. 4242 "Monobloc" Very rare 35mm bubble back, a super rare piece that is rarely seen in bubble backs equipped with Cal. It is called "Monobloc" because it has the same one-piece 35mm diameter two-piece case and back cover as the 1st Oyster Chronograph Ref. 3525 of the same age. The dial is a 3-backerel design, which is also seen in bubble backs of the same era, and it is a precious gem with a unique aspect and wonderful taste of this era that cannot be seen in the semi-bubble backs and big bubble backs of later years in the big size bubble backs. It is equipped with an in-house made automatic movement Cal.NA, which was used for bubble backs of the same age.