After five years of design and preliminary work, the Zenith El Primero was introduced to the public in March of 1969. The complexity and movement of the watch makes this timepiece stand out from all other watches of its time. From its exquisite design to the remarkable movement and preciseness, the El Primero introduced something the watch industry had never seen before.

The El Primero was the first self-winding chronograph calibre with an oscillating weight rotating on a centrally positioned ball bearing. The calibre has thirteen diameter lines that incorporate a thin 6.5 mm thickness. The movement is run by a column wheel and classic reset hammers.

Because of the unique build and the impeccable balance, the Zenith El Primero is one of the most precise and accurate of all movements. It is all because of the glucydur balance wheel that is combined with a flat spiral spring. The flat spiral spring is made from nothing other than the top quality non-magnetic self-compensating Anachron oscillates, and works at a rate of 36,000 vibrations per hour. Because of this incredible rate, the El Primero is able to produce chronometer measurements of up to one-tenth of a second.

The movement of the watch is comprised of 354 parts, with many of the parts being different from one another. On one of the most complex versions, there will be over 250 different parts. Because of the multitude of parts, the movement is not affected by any sudden changes or magnetic fields. To ensure this, over fifty different points are oiled using ten different grades of lubricant.

It is certainly not a quick and painless task to put together a watch like the Zenith El Primero. Every little detail is inspected by a number of different people within the factory. The total process to create the wondrous movement of this timepiece consists of nine hard months of work. Every part within the watch will see anywhere between five and fifty inspections and operations. Along with the inspections, there are around fifty milling procedures on the dial side and 77 milling procedures on the bridges side.

The complexity and precise craftsmanship from every specialist watchmaker has proved to be effective in the building of the Zenith El Primero timepiece over the past 30 years. With a plethora of parts and a number of inspections put into a grueling 9 month process, every El Primero watch on the market is built to perfection.