In 1963, production of the COSMOGRAPH began with the reference 6239, initially with a VALJOUX 72B movement, and identical to that of the 6238 models.
In 1965, the first model with screw-in buttons was produced.
TheDAYTONAboom started in Italy in 1985, when a magazine published on its cover the photo of G. Agnelli, arm resting on the mast of a boat, wearing a classic 6263 with light-coloured dial. A simple photo that would breath new life into a model that for 22 years had never really found its public.
- Movement: Swiss Valjoux 7750 ETA Automatic Chronograph
 - Functions: hours, minutes, seconds, fully functioning Chronos, Minute and hour totalisators activated by push buttons, button at 2 starts/stops chronograph, button at 4 resets chronograph, Stopwatch Feature Available Exactly like the Authentics, Seconds Hand Functions at the 6 OClock Sub Dial.
 - Size: diameter 40 mm, height 14 mm
 - Case: Solid Stainless Steel, screw-in button with a crown logo.
 - Dial: light green, three subdials
 - Genuine scratch-resistant, pressure-proof sapphire crystal glass.
 - Strap/Bracelet: Green Genuine leather band
 - Smooth sweeping second hand,exactly like the real Rolex
 - Double locking security clasp
 - Green Rolex hologram sticker on the back
 - Screws in the links not pins
 - Serial/band number on last link/lugs
 - Serial number between the lugs
 - Serial number on clasp
 - Laser etched Rolex crown at 6
 - Waterproof (can be worn for regular swimming with no problems)
 - Power reserve approx. 42 hours.
 - No docs and box