Rolex Daytona

They were coming from Zenith.

There are two series of the Rolex Cosmograph Daytona. The original series, produced in small quantities from the early 1960s to the later 1980s, has a four-digits model or reference number, for example the reference 6263. This original series eventually became iconic[vague] but in very short supply in the early 1990s, which led to a second series to meet demand. This second series was a Zenith modified movement, the five digit series movements noted by dropping the "1" from the current 6 digit code is notably the most accurate of all movements whose pedigree is in the famous Zenith "El Primero" movement. This movement was originally manufactured and released in the '60s and is still the highest VPH mass produced movement on the market at 36,000 VPH. The "El Primero" movement is often considered the hallmark of chronographs for accuracy and reliability.

Rolex purchased these movements for the Daytona and then modified the movement from 36,000VPH to 28,800VPH and made a few other subtle changes. These later series Daytonas prior to in-house movements were produced from 1988 to 2000 and represent the time period where Rolex Daytonas really began cult status, due to its limited production, accuracy, reliability and limited supply as they were coming from Zenith. This Zenith based movement is often considered more accurate and reliable than any other movement in the Chronograph space, including the current in-house Rolex Daytona model.

The current series, the Rolex in-house made movement, has a six-digit reference number, for example reference 116520. The new six-digit Daytonas are certified, self-winding chronometers with chronograph functions. Rolex was, and remains today, a sponsor of the 24 Hours of Daytona race at the time, and named its chronograph watch after that famous race.