Zenith EL PRIMERO 21 9004 Mode D'emploi page 10

2 > WINDING THE WATCH
Your watch is fitted with an automatic mechanical movement. The
movement is wound via the crown or the effect of the oscillating
weight. Winding via the oscillating weight takes place when the
watch is on your wrist.
When your watch has stopped
The crown must be in the position 0, meaning it should be
pressed against the case.
With the watch in your hand, turn the crown counter-clockwise.
Turn the crown 72 times to fully wind the watch. The barrel that
contains the mainspring has now been wound. In order for the
automatic winding to work properly, the watch must be worn
for at least 12 hours per day, for several days. Not wearing the
watch enough causes it to stop.