ROLEX. A STAINLESS STEEL CHRONOGRAPH WRISTWATCH WITH BRACELET

Reference 6240 was introduced in late 1965 as the first waterproof Cosmograph model to be produced by Rolex. This new innovation was predominantly characterized by the introduction of screw-down chronograph pushers in addition to the screw-down crown. In production only during the second half of the 1960s, it is thought that no more than 1750 examples were made. The reference 6240 was in essence an experimental model which Rolex used in order to trial different dial designs and to perfect the waterproofness of the model which emerged fully as the now better known references 6263 and 6265.