Zenith EL PRIMERO 21 9004 Mode D'emploi page 8

1 > EL PRIMERO 21 MOVEMENT
In front of you is the El Primero 21 movement. It is the only
mechanical 1/100th of a second chronograph movement.
The El Primero 21 movement is a masterpiece of modern
engineering. Constructed using state-of-the-art methods and
finished using the newest technologies and materials, this
movement fulfils two objectives: a finish of the highest possible
quality, and optimum performance and accuracy on the wrist.
First released in 1969, the world's most accurate series-made
chronograph entered a new era of mechanical timekeeping with
the El Primero 21 movement.
An impressive frequency of 360,000 vibrations per hour is
testament to the groundbreaking ingenuity of Zenith, and enables
precise measurement of time periods to a hundredth of a second.
The jump from tenths to hundredths of a second is a quantum leap
in terms of watchmaking performance and engineering.
For Zenith, accuracy is the absolute priority. To avoid any risk
of the chronograph affecting the accuracy of the time display,
the El Primero 21 movement is equipped with a "double-chain
structure".