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Zenith El Primero 400

Probable

One of the first automatic chronographs, and the base of the Rolex caliber 4030 used in the Daytona 16520 — where Rolex reduced the frequency to 28,800 and substituted its own escapement and balance. A 16520 movement is therefore an El Primero derivative and not an El Primero.

Specifications

Movement manufacturer
Zenith
Production
1969–present
Frequency
36,000 vph (5 Hz)
Jewels
31
Power reserve
50 hours
Winding
automatic
Complications
Chronograph · Date · Small seconds

Architecture

Integrated automatic chronograph with a column wheel, running at 36,000 vph — high enough to resolve a tenth of a second, which is the caliber's defining claim.

Related calibers

  • Succeeded by

    Rolex 4130

    Via the 4030; the 4130 replaced the El Primero-based Daytona movement in 2000.

  • Derivative

    Rolex 4030

References using this caliber

No catalog references are linked to this caliber yet.

Provenance of this record

Sources & Evidence

Secondary sourceCollector research

Ranfft Watch Movement Archive

Dr. Roland Ranfft (archived and maintained by volunteers)

Accessed
2026-08-18

Cited for

This referenceProbable
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Last verified: Not yet reviewed