References 476% CONFIDENCEOverall confidence: 76%How well the pin's source and references back up its dates.Weighted average of how firmly 4 references, the source included, support the pin's start and end times; a reference counts half as much for every 180 days older than the newestShow all pins at 75% confidence or better
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
- [1]90%en.wikipedia.org/wiki/Zenith_(watchmaker)en.wikipedia.org· Posted Oct 5, 2026· Starts Jan 10, 1969 ✓· 25% of score
Wikipedia's[3][4] Zenith page: "El Primero calibre, when it was first unveiled on 10 January 1969, was the first high frequency automatic chronograph movement"; Analog:Shift says "Zenith announced the El Primero on January 10, 1969".
- [2]70%Zenith El-Primero - Analog:Shiftanalogshift.com· Added Oct 5, 2026· 25% of score
"Zenith announced the El Primero on January 10, 1969"; development began in 1963 for the 1965 centennial.[1]
- [3]75%Chronograph - Wikipediaen.wikipedia.org· Added Oct 5, 2026· 25% of score
"Zenith pre-empted them by unveiling their automatic chronograph 'El Primero' on January 10th, 1969."[1]
- [4]70%Rolex Cosmograph Daytona - Wikipediaen.wikipedia.org· Added Oct 5, 2026· 25% of score
The second Daytona series used Zenith's El Primero movement, 36,000 vph.[1]
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