Launched in 1939, reference 3525 was Rolex’s very first chronograph to be housed inside an Oyster case, with a screw-down case back and winding crown. Rose gold specimens are by far the rarest produced for this model, making the watch in this catalogue exceedingly rare. Another element of interest is its serial number: most of the production for the reference is grouped in three batches, with respectively serial numbers around 40000/50000 for the first batch, in the mid 100000 for the second, and in the mid 300000 for the last; this watch is part of the early examples produced, featuring for this reason a "transitional" straight logo dial (inherited from the previous models with snap-on case backs). Furthermore, first generation specimens have serial numbers stamped on the case back, while later examples feature these numbers in between the lugs.